OPINION
Before CHAMBERS, KOELSCH, BROWNING, DUNIWAY, ELY, HUF-STEDLER, WRIGHT, TRASK, CHOY, GOODWIN, WALLACE, SNEED and KENNEDY, Circuit Judges. ELY, Circuit Judge:The appellant, in his third trial, was convicted of the offense of bank robbery. 18 U.S.C. § 2113(a), (d). In urging reversal, the appellant presents several contentions, only one of which need now be reached. This is the contention, with which we agree, that reversal is required because of the failure of the District Court to comply with the plain requirements of Fed.R.Crim.P. 24(c). The circumstances giving validity to this contention are briefly and accurately summarized as follows:
After instructing the jury, the district judge told an alternate juror that she *1155was excused and would be permitted to go home, but asked her to “stand by” in case it was “necessary for [her] to come in.” After almost four hours of deliberation spread over two days, the jury returned a verdict of guilty. The judge refused to accept the verdict because of his belief that the verdict was inconsistent with the instructions.
The district judge then announced that when he returned from a luncheon recess he found a note from one of the jurors, which stated:
“Your Honor, due to the sudden accidental death of one of my close coworkers during the course of this trial, I feel emotionally unable to come to a decision.”
The district judge then remarked that at the time he received the note he called the alternate juror and asked her to return to court, but that, when he was later told that the jury had reached a verdict, he had called the alternate back and told her by telephone not to return. But after questioning the original juror who wrote the note, the district judge excused the note-writing juror and asked defense counsel if it would be agreeable to him that the alternate juror be substituted. Defense counsel objected to this procedure and promptly made a motion for a mistrial, which was denied. Over defense counsel’s objection, the alternate juror joined the jury upon her arrival an hour later. The instructions were then reread, and the court advised the jury to “begin at the beginning, and begin all your deliberations just as if the case had been submitted to you this instant.” After twenty-nine minutes of deliberation, the newly constituted jury found the appellant guilty a second time.
Fed.R.Crim.P. 24(c) states in pertinent part:
“Alternate jurors in the order in which they are called shall replace jurors who, prior to the time the jury retires to consider its verdict, become or are found to be unable or disqualified to perform their duties. . . . An alternate juror who does not replace a regular juror shall be discharged after the jury retires to consider its verdict. .” (Emphasis added.)
Two other Courts of Appeals that have considered the question have held that the requirement that the alternate shall be discharged after the jury retires is a “mandatory” requirement that should be followed because “. . . any benefit to be derived from deviating from the Rule is unclear and the possibility of prejudice so great.” United States v. Allison, 481 F.2d 468, 472 (5th Cir. 1973), subsequent appeal, 487 F.2d 339 (5th Cir. 1973), cert. denied, 416 U.S. 982, 94 S.Ct. 2383, 40 L.Ed.2d 759 (1974);1 United States v. Hayutin, 398 F.2d 944 (2d Cir.), cert. denied, 393 U.S. 961, 89 S.Ct. 400, 21 L.Ed.2d 374 (1968),2 subsequent appeal *1156sub nom., United States v. Nash, 414 F.2d 234 (2d Cir.), cert. denied, 396 U.S. 940, 90 S.Ct. 375, 24 L.Ed.2d 242 (1969). The unambiguous language of the Rule and the cases interpreting it3 have impelled one of the Nation’s most prestigious legal commentators to conclude that “. . . it is reversible error, even though defendant may have consented, to permit an alternate to stay with the jury after they have retired to deliberate or to substitute an alternate after deliberations have begun.” C. Wright, Federal Practice and Procedure § 388, Vol. 2 at p. 52 (1969).4 In his discussion, Professor Wright criticizes our court’s Leser decision, discussed infra.
The Rule is phrased in mandatory terms for what many have thought to be sound reasons.5 Among such reasons are: The inherent coercive effect upon an alternate juror who joins a jury that has, as in this case, already agreed that the accused is guilty is substantial. Moreover, such a procedure significantly limits the accused’s right to a mistrial if the original jury cannot reach agreement. A lone juror who could not in good conscience vote for conviction could be under great pressure to feign illness or other incapacity so as to place the burden of decision on an alternate juror.6
That impermissible coercion upon the alternate juror in this case was manifestly inherent, and that there was not the conscientious, careful reconsideration by the twelve of the newly constituted jury would seem apparent from the fact that, despite the district judge’s instruction to the jury to “begin at the beginning,” a jury that had required almost four hours to reach its initial verdict needed, after being reconstituted, only twenty-nine minutes to find the appellant guilty a second time.7
*1157The prosecution argues that we should infer from the record that there had been a stipulation in this case of the type found in Leser v. United States, 358 F.2d 313 (9th Cir. 1966), petition for cert dismissed, 385 U.S. 802, 87 S.Ct. 10, 17 L.Ed.2d 49 (1966), wherein we held that, because of the previously expressed stipulation, an alternate juror could be substituted despite Rule 24(c). There is absolutely no basis in the present record for the conclusion that there was such an agreement. The record clearly reveals the defense attorney’s vigorous objection to substitution of the alternate juror under conditions that the attorney properly characterized as “a very unusual circumstance and very unforeseeable.” We cannot agree with the prosecution, on the authority of a case involving an express stipulation in explicit detail, that defense counsel’s failure to object to a routine admonition to an alternate to “stand by” rises to the level of an express agreement to a procedure clearly infringing the unambiguous, mandatory prohibition of Fed.R.Crim.P. 24(c).
Moreover, even had there been such a stipulation before the jury retired, we could not hold that such a stipulation would remain effective after dramatic changes of circumstances, including the original jury’s arrival at a guilty verdict and the court’s telephone call to the alternate juror to advise her that her services would no longer be required because the original jury had reached a verdict. Indeed, it is doubtful, after the court informed the alternate juror she would no longer be needed, that this juror remained as a qualified alternate. In realistic effect her release by the court, even though it developed to be only temporary, relieved her of all obligations of the usual juror, including the obligation of confidentiality. There is no way by which one could ascertain, from the record before us, whether the alternate juror discussed the case with others after she was told not to return because the original jury had reached a verdict, and if so, the scope and extent of any such discussion.
Reversed and remanded.
. In Allison, the court wrote:
“The provision of Rule 24(c) that an alternate juror who does not replace a regular juror ‘shall be discharged after the jury retires to consider its verdict’ is a mandatory requirement that should be scrupulously followed. Because any benefit to be derived from deviating from the Rule is unclear and the possibility of prejudice so great, it is foolhardy to depart from the explicit command of Rule 24. Moreover, there is no rule providing that the parties, or the district court, may stipulate that an alternate be present during the jury’s deliberations.” 481 F.2d 468, 472.
. In Hayutin, the court remarked:
“The provision of Rule 24(c) that an alternate juror who does not replace a regular juror ‘shall be discharged after the jury retires to consider its verdict’ is a mandatory requirement
“In the face of the mandatory requirement of Rule 24(c) and the Committee’s failure at the time of its adoption to include a proposal to permit an alternate juror to replace a regular juror during their deliberations, it is difficult to understand what purpose is to be served by retaining the alternate jurors once the case has been submitted. The reason advanced by the Government in its brief that this procedure presents counsel with the choice of consenting to a substitution if one of the regular jurors became disqualified ‘prior to the end of jury deliberations’ rather than face a retrial or proceed with less than twelve, is no reason in the absence of any rule or statute authorizing such consent. The absence of benefit being so clear and the danger of prejudice so great, it seems foolhardy to depart from the command of Rule 24.” 398 F.2d 944, 950.
. Neither Allison nor Hayutin held that the violation of Rule 24(c) is, ipso facto, such prejudicial error as to necessitate reversal in all circumstances. In both cases the convictions were ultimately affirmed, the court in Allison finding that there was “no reasonable possibility” that the Rule 24(c) violation “affected the verdict" (487 F.2d at 339), and the court in Hayutin concluding that there was “not a scintilla of evidence that the defendant Leon Nash was prejudiced” by the Rule’s infringement (414 F.2d at 236). In both Allison and Hayutin one or more alternate jurors were not discharged after the jury retired, but it was found that there was no possibility of any prejudice to the defendant in either case because the altemate(s) did not participate in the jury’s deliberations in any way. Thus, the defendants in both cases received the careful deliberation of the original twelve-member juries, free of any participation by the alternates. Here, however, the alternate did participate, after having been previously excused. In these circumstances, the distinct probability of prejudice to the accused is a fact that we cannot ignore. When, as here, an alternate juror is permitted to participate in the jury’s deliberations after the original jury has retired for deliberations, the violation of the plain prohibition of the Rule is so patently impermissible that the “possibility of prejudice,” in the language of Allison, is manifest.
. The appellant argues that the juror substitution that occurred here violated Lamb’s right to due process of law as guaranteed by the Fifth Amendment. Since the plain language of the Rule was violated, we need not reach any alleged constitutional issue, and we express no opinion thereon. We do note, as a historical fact only, that a rule permitting substitution of an alternate juror after final submission eventually was withdrawn from a 1941 draft by the original Advisory Committee on Criminal Rules when the Supreme Court inquired whether the Committee had satisfied itself that such a provision would be desirable or constitutional. Orfield, Trial Jurors in Federal Criminal Cases, 29 F.R.D. 43, 46 (1962).
. A procedure that would permit substitution of an alternate juror after deliberations have already commenced was rejected by the American Bar Association Project on Minimum Standards for Criminal Justice, in its approved draft of Standards Relating to Trial by Jury. See ABA Project on Minimum Standards for Criminal Justice, Standards Relating to Jury Trial. (Approved Draft, Section 2.7 at p. 326 (1974).) See also Report of the Jury Committee of the Judicial Conference of the United States (March 1973 at 7-8) (disapproving a proposed revision of Rule 24(c) that would retain jurors for possible substitution after deliberations have begun).
. See C. Wright, Federal Practice and Procedure § 388, Vol. 2, at 53 n. 17 (1969).
. While we have noted the obvious coercive effect suggested by the final deliberative period of only twenty-nine minutes, that is not a factor contributing to our conclusion in this case. The mandatory provision of Rule 24 having been violated, the period of time during which the substitute juror participated in the deliberations is essentially irrelevant.