delivered the opinion of the Court.
This is an original proceeding in which relator, David R. Womack, seeks a writ of mandamus directing Honorable Charles D. Berry, Judge of the 8th District Court of Hopkins County, to set aside an order granting, pursuant to the provisions of the Soldiers’ and Sailors’ Civil Relief Act of 1940 as amended,1 a stay of proceedings pending in said court. Since the cause of action asserted by relator does not affect the defendant who is in military service and can be tried separately without prejudice to any of the parties, we have concluded that the court should order a separate trial of such cause of action and proceed to trial thereon.
R. M. Womack died testate in 1948, survived by two sons, W. B. Womack and relator, and by three grandchildren, Michael A. Patton, Kathleen E. Patton and Robert M. Patton, who are the children of the testator’s deceased daughter, Mrs. Edna Womack Patton. After directing that the testator’s estate be divided into three equal parts and that the two sons should each take one of such parts, the will provides that the remaining one-third be held in trust by W. B. Womack for the three grand*46children equally; that the trustee shall have complete control of the trust property to handle as he might deem best, but shall hand the same over as the grandchildren, respectively, reach the age of twenty-one; that if any grandchild interferes with W. B. Womack, such grandchild shall take only one dollar from the 'estate; that the testator, his associates in the City National Bank of Sulphur Springs, and W. B. Womack have handled the affairs of Mrs. Edna Womack Patton since her death; that if any grandchild attempts to make claims against the bank or other parties arising out of the handling and management of Mrs. Patton’s estate, such grandchild shall take only one dollar from the testator’s estate; that as each grandchild reaches the age of twenty-one years and is about to receive a portion of the testator’s estate under the will, such grandchild shall release the bank, its officers and W. B. Womack from all claims arising out of the handling of Mrs. Patton’s estate; and that in the event W. B. Womack predeceases relator, the latter shall carry out the terms of the will as trustee with all the benefits, terms and instructions as set out therein.
W. B. Womack died in 1952. On October 8, 1953, relator instituted suit to recover possession of the property left in trust for the three Patton children, asserting that he is entitled to hold and manage the same as the successor trustee named in the will. Michael became twenty-one years of age on the day the suit was filed, and is the defendant whose military service is the basis of the stay ordered entered by the trial court. Kathleen and Robert are minors, and their father, M. L. Patton, is guardian of their estates.
The original petition named M. L. Patton, guardian of the estates of Kathleen and Robert, John H. Stegner, executor of the estate of Louise S. Womack, and Michael A. Patton as defendants. It is there alleged that the will of R. M. Womack was admitted to probate and W. B. Womack qualified as executor of the estate; that W. B. Womack took possession of and co-mingled the trust estate with his individual property; that W. B. Womack left a will in which Louise S. Womack is named as principal beneficiary and independent executrix without bond; that Louise S. Womack came into possession of part of the trust estate after the death of W. B. Womack; that Louise S. Womack died in May, 1953, and John H. Stegner was appointed and qualified as executor of her estate; that the inventory of M. L. Patton, guardian, includes property which was listed in the inventory of the estate of R. M. Womack; that if any of the property in the guardian’s hands is part of the trust estate, *47relator is entitled to possession thereof; that W. B. Womack did not file income tax returns for the trust estate; that Michael should not receive his share of the trust estate, because relator expects to file proper income tax returns and Michael should be required to pay his share of the taxes and other expenses, including those incurred by relator in filing and prosecuting the suit. Relator prayed for judgment against each defendant for possesison of any of the trust property held by the latter and for the value of the property of the trust that each defendant, being liable therefor, failed to deliver, that the defendants be enjoined from delivering any of the trust estate to Michael, and that Michael be enjoined from receiving or disposing of any of the trust property.
It is necessary to set out in some detail the subsequent pleadings and proceedings in the trial court. Defendants first answered with a general denial. Thereafter, in compliance with an order of court directing that they file statements under oath showing the location and disposition of the trust property, the defendants filed separate verified reports. M. L. Patton, guardian, stated that after the death of R. M. Womack there was delivered to him as the property of his three children certain stocks, proceeds of insurance policies, and cash, a list of which is set out in the report, aggregating approximately $74,000.00; that such property represents one-third of all property owned by R. M. Womack at the time of his death; and that the guardian delivered to Michael the latter’s share on October 8, 1953. Michael stated that he has in his possession, subject to such limitation as exists by reason of the suit, all property belonging to his estate theretofore handled by his father, which includes one-third of all property shown in the statement of M. L. Patton. Stegner stated that he does not have possession of any trust property.
Michael then applied for and was granted, over the protest of relator, leave to implead and file a cross-section against The City National Bank of Sulphur Springs. On December 29, 1954, he filed his first amended original answer and cross-action, alleging that W. B. Womack as executor of the estate of R. M. Womack administered such estate and after paying the claims distributed the estate one-third each to W. B. Womack and relator and one-ninth each to Michael and his brother and sister; that Michael’s share has been handled by his father in a satisfactory manner; that relator is not entitled to possession thereof and should be removed as trustee; that the bank is a depository of a substantial amount of his estate and is demand*48ing a release from all the beneficiaries under the will, which constitutes a cloud on his property. He prayed that relator be denied possession of, and that the bank be required to relinquish any control which it might be asserting over, any of Michael’s property. In a separate pleading, filed on January 18, 1955, and denominated a supplemental petition, Michael alleged that as a result of the bringing of the suit and the relator’s communications with companies in which Michael owns stock, the latter has incurred attorney’s fees and has been prevented from selling his stocks or receiving the dividends thereon, and prayed for judgment against relator for damages in the amount of $12,500.00.
Several days prior to the filing of such supplemental petition, Michael and his father filed a joint motion to stay the proceedings in the case, alleging that the former had been inducted as a Naval Aviation Cadet to serve for a period of four years ending on August 17, 1958, and praying that the proceedings be stayed until that date.
On January 21, 1955, relator filed his first amended original petition complaining of M. L. Patton, guardian, and John H. Stegner executor, and seeking to recover only the property left in trust for Kathleen and Robert; no relief is sought against Michael or his property, and the suit against him is expressly dismissed with prejudice.
Three days later the bank filed its original answer and cross-action, alleging that it has money on deposit in Michael’s account, some of which is part of his inheritance under the R. M. Womack will; that some of the property originally owned by the estate of R. M. Womack is on deposit in the bank to the account of various parties to the case; that various parties have made demands on the bank for the delivery of its deposits and funds; and that the bank is unable to determine its liability, if any, created by the will of R. M. Womack when considered in connection with the estates of the three Patton children. It prayed for a declaratory judgment construing the will to determine whether a valid trust was created in W. B. Womack as trustee and relator as successor trustee, whether the original trustee was authorized to deliver the trust property to the beneficiaries, and whether each child is now entitled to receive his or her inheritance. It also requested the court to determine and adjudicate the property controlled by the will, and to enter judgment releasing the bank from all liability by virtue of its *49having been depository of funds belonging to the estate of R. M. Womack and by virtue of any connection it might have had with funds belonging to any of the parties to the suit.
Relator answered the motion to stay the proceedings, praying that the same be defined, or in the alternative that the court grant a separate trial of all claims and issues relating to Michael and stay only the trial of such claims and issues. After a hearing on January 25, 1955, the trial court overruled relator’s motion for a separate trial and granted Michael’s motion for a stay of the proceedings. Relator’s subsequent motion to set aside such order was overruled, and his application to the Court of Civil Appeals for a writ of mandamus was denied in an unpublished opinion.
The federal statute provides that any action in which a person in military service is involved, either as plaintiff or defendant, shall on application by such person be stayed as provided in the Act unless in the opinion of the court the ability of such person to prosecute the action or conduct his defense is not materially affected by reason of his military service. Its obvious purpose being to prevent prejudice to the rights of a litigant in military service because of inability to prosecute his claim or conduct his defense, the statute should be liberally construed and applied to accomplish that purpose. It should not, however, be used as a device to delay the proper and expeditious determination of legal proceedings when the rights of the party in military service will not be materially affected thereby. The trial court is given a wide discretion in determining whether a stay should be granted under the circumstances of a particular case and in deciding which party should carry the burden of proof on the issue of prejudice. See Boone v. Lightner, 319 U. S. 561, 63 S. Ct. 1223, 87 L. Ed. 1587.
Relator’s amended petition asserts only the right to take possession of and manage the property left in trust for Kathleen and Robert. His right to prevail depends upon whether he, as the successor trustee named in the will, is entitled to possession of such property during the minority of the beneficiaries. Michael is twenty-one year of age, and under the provisions of the will is now entitled to his property even though it might be determined that during his minority the same should have been held by the trustee. It clearly appears from the pleadings and verified reports that Michael has received all property to which he is entitled under the will, that he is satisfied with his father’s management thereof during his minority, and that the guardian *50and possibly the two minor children and the bank have possession of the property devised in trust for Kathleen and Robert. We are unable to perceive, therefore, how Michael could be affected in any way by a determination of the claims of the other parties with reference to the property of the minors. Assuming that the cause of action which relator originally alleged against Michael and his property is effectively dismissed with prejudice, which will be discussed later, no one with the possible exception of the bank is questioning Michael’s right to possession, management and control of his property.
Michael is interested, however, in his cross-action against relator for damages, in his action against the bank to obtain a release of his property, and in any claims or questions which the bank might raise affecting his property. If these actions and issues are to be determined in connection with and as a part of the trial of the main suit, then it cannot be said, on the record in this case, that the trial court abused its discretion in staying the entire proceedings. If, on the other hand, a separate trial of such actions and issues had been granted, the federal statute would afford no basis for staying the trial of the main case. We must determine, therefore, whether mandamus should issue to compel the trial court to order a severance.
The Rules of Civil Procedure bestow upon trial courts broad discretion in the matter of consolidation and severance of causes, and the trial court’s action in such procedural matters will not be disturbed on appeal except for abuse of discretion. See Hamilton v. Hamilton, 154 Texas 511, 280 S.W. 2d 588. This brings us to the most serious question in the case. It is well settled that mandamus lies to enforce the performance of a ministerial act or duty, or to require the exercise of discretion. Many of our decisions declare, without qualification or exception, that the writ will not issue to review or control the action of an inferior court or public officer in a matter involving discretion. Lauraine v. Ashe, 109 Texas 69, 191 S.W. 2d 563; 196 S.W. 501; McDowell v. Hightower, 111 Texas 585, 242 S.W. 753; Anchor v. Martin, 116 Texas 409, 292 S.W. 877; Morton’s Estate v. Chapman, 124 Texas 42, 75 S.W. 2d 876; 28 Tex. Jur. 574, Sec. 33. And it has been held that the determination of the issues of severance invokes the discretionary or judicial powers of the trial court and is not subject to control by mandamus. Baten v. Campbell, 62 S.W. 2d 1010 (no writ).
The rule denying mandamus with respect to matters of a discretionary character is not without limitation, however, and *51the writ may issue in a proper case to correct a clear abuse of discretion. See City of Houston v. Adams, 154 Texas 448, 279 S.W. 2d 308; Stakes v. Rogers, 139 Texas 650, 165 S.W. 2d 81; City of San Antonio v. Zogheib, 129 Texas 141, 101 S.W. 2d 539; Arberry v. Beavers, 6 Texas 457, 55 Am. Dec. 791; King v. Guerra, 1 S.W. 2d 373 (writ ref.); 55 C.J.S. 100, 126, Secs. 63 and 73; 34 Am. Jur. 858, Sec. 69; 35 Am. Jur. 31, Sec. 259. While no Texas case has been found in which the writ issued to correct the action of an officer or tribunal in a matter of discretion, the cited cases recognize the exception to the general rule.
Rule 174(b), Texas Rules of Civil Procedure, provides that the court in furtherance of convenience or to avoid prejudice may order a separate trial of any claim, cross-claim counterclaim or third party claim, or of any separate issue, or of any number of such claims or issues. The use of the permissive word “may” imports the exercise of discretion in such matters. But the court is not vested with unlimited discretion, and is required to exercise a sound and legal discretion within limits created by the circumstances of the particular case. The express purpose of the rule is to further convenience and avoid prejudice, and thus promote the ends of justice. When all of the facts and circumstances of the case unquestionably require a separate trial to prevent manifest injustice, and there is no fact or circumstance supporting or tending to support a contrary conclusion, and the legal rights of the parties will not be prejudiced thereby, there is no room for the exercise of discretion. The rule then is peremptory in operation and imposes upon the court a duty to order a separate trial. While the refusal to grant a separate trial under such circumstances is usually termed a clear abuse of discretion, it is nevertheless a violation of a plain legal duty. If it also appears that the injustice resulting from such refusal cannot later be remedied on appeal, the action of the court is subject to control by mandamus.
A granting of relator’s motion for a separate trial of his suit might be contrary to the personal wishes of the other parties, but in a legal sense would not prejudice the latter in any way. Relator’s claim as stated in his amended petition is a distinct and severable part of the entire controversy. The dismissal of his suit against Michael does not affect the latter’s right to be heard on his claims for affirmative relief. But the determination of Michael’s actions for damages and to recover his property, as well as any questions raised by the bank regarding *52such property, involves no issue which has any bearing on relator’s right to possession of the property of the minors. Michael has no pecuniary interest in and will not be affected by a separate trial of the main suit, and the bank’s interests can be as fully protected in separate trials as in a single trial.
The court overruled the motion for a separate trial and granted Michael’s motion that the proceedings be stayed until August 17, 1958. On that date Kathleen will be over twenty-one years of age, and Robert will be almost twenty years old. The latter will probably reach his majority before the case can be tried and appealed. In practical effect, therefore, the action of the trial court denied relator a judicial determination of his right and duty to administer the property left in trust for the minors. By simply granting relator’s motion for a separate trial, the court would have been in position to hear relator’s suit promptly and stay only the proceedings relating to Michael and his property. Under these circumstances we think it was clearly the duty of the court to order a separate trial.
The record does not disclose whether the court has entered an order dismissing relator’s suit as to Michael. The question of whether a plaintiff may, without permission of the court, discontinue his suit as to one or more of several defendants who have been served with process, or who have answered, has not been decided. See Rule 163, Texas Rules of Civil Procedure; Ridley v. McCallum, 139 Texas 540, 163 S.W. 2d 833. Nor is it necessary for us to decide the question here. Relator’s amended petition expressly dismisses his suit as to Michael with prejudice. Michael will be fully protected, and the parties other than relator will not be adversely affected by such dismissal. Under these circumstances the trial court is under a duty to order the dismissal. Since relator’s ultimate right to a writ of mandamus will not depend upon whether the court grants or refuses permisison to dismiss, no useful purpose would be served by requiring relator to obtain action by the court on that matter before we consider his petition for mandamus.
It is our opinion that the trial court should: (1) order a dismissal of relator’s suit against Michael A. Patton with prejudice as to relator, but without prejudice to the rights of Michael A. Patton and the bank to be heard on their cross-actions: (2) order a separate trial of relator’s suit to recover the- property devised by the will of R. M. Womack in trust for Kathleen E. Patton and Robert M. Patton, and certain related issues raised by the bank’s cross-action as set out below; and *53(3) set aside the order staying proceedings entered on January 25, 1955, in so far as such order is applicable to the trial of relator’s suit and the issues to be determined in connection therewith.
There are a number of questions raised by the bank’s cross-action which are closely related to, and should be disposed of in connection with relator’s suit. At the time such suit is tried, therefore, the court should decide whether the will of R. M. Womack created in W. B. Womack as trustee, and relator as successor trustee, a valid trust in the property bequeathed to the minors, whether the original trustee was entitled to deliver such property to the minors, and whether each minor is now entitled to receive his or her inheritance. The court will also be authorized to and should discharge the bank from liability with respect to any property of the minors which the bank is required to and does surrender upon final determination of relator’s suit. This affords the bank ample protection on that phase of the case, and renders it unnecessary to hold relator’s suit in abeyance until the remaining issues raised by the bank’s cross-action are decided.
Relator, Michael, M. L. Patton, guardian, and John H. Stegner, executor, are made cross-defendants in the bank’s cross-action. The dismissal of relator’s suit as to Michael does not eliminate the latter as a party defendant to such cross-action, and hence does not deprive the court of jurisdiction to determine, in connection with relator’s suit, the related questions raised by the bank. But, as pointed out above, the decision of these matters cannot affect Michael or his property, and should not be stayed on his account.
The bank also asserts the right to a judicial determination of the property controlled by the will and to a general release from all liability by virtue of having been depository of funds belonging to the estate of R. M. Womack and by virtue of any connection it might have had with funds belonging to any of the parties to the suit. If the bank is entitled to such relief, it will be necessary for the court to ascertain and trace the property owned by R. M. Womack at the time of his death, and determine whether the bank has incurred any liability to his estate or to any of the parties to the suit. Michael is interested in these matters, as well as the question of his present right to possession of his inheritance, and the same should not be tried in connection with relator’s suit.
*54We assume that the trial court will enter proper orders in accordance with this opinion, but in the event such orders are not entered, the clerk will be instructed to issue the appropriate writ.
References have been made in this opinion to the provisions of the will of R. M. Womack, the property devised thereby in trust for various persons, and the pleadings and positions of the parties. We are not to be understood as expressing an opinion with respect to the meaning and effect of the will, the sufficiency of the pleadings, the propriety of permitting Michael to file a cross-action against the bank, or the bank’s right to the relief which it seeks.
Opinion delivered June 6, 1956.
U.S.C.A. App., Sec. 521.