The US military's outgoing top commander, Gen Peter Pace, says he opposed the decision to replace him at the end of his first term.
Gen Pace has been criticised for his handling of the Iraq war
Gen Pace said he did not resign voluntarily as he felt this would be "unacceptable" for him as a leader. "I've been told I'm done," he said.
His term as chairman of the Joint Chiefs of Staff is to end in October.
Washington said last week it would not seek another term to avoid a "divisive" confirmation process in Congress.
The Bush administration has faced several challenges on Iraq in recent months from Congress, which is now controlled by the Democrats.
Gen Pace has been involved in all the controversial decisions surrounding the US military presence in Iraq and Afghanistan.
He is regarded as a close ally of former Defence Secretary Donald Rumsfeld, who resigned last year amid criticism of his handling of the Iraq war.
Gen Pace told an audience at the Joint Forces Staff College in Norfolk, Virginia, that he felt resigning during a war would be a betrayal of his troops.
"One thing that was discussed was whether or not I should just voluntarily retire and take the issue off the table," he said.
But, he said, he rejected this because he did not want anyone under his command to "think - ever - that his chairman, whoever that person is, could have stayed in the battle and voluntarily walked off the battlefield."
US Defence Secretary Robert Gates last week said he had intended to seek another two-year term for Gen Pace but chose to avoid a "a backward-looking and very contentious process".
He recommended Adm Michael Mullen, the current chief of naval operations, as his replacement.
He said Adm Mullen had the "vision, strategic insight and integrity to lead America's armed forces".
On Thursday, Democrat Senate Majority Leader Harry Reid took the unusual step of openly criticising Gen Pace.
Senator Reid said he had told Gen Pace "he had not done a very good job of speaking out for some obvious things that weren't going right in Iraq".