[13] On December 23, 2020, Prime Minister Justin Trudeau announced that McDonald would succeed General Jonathan Vance as Chief of the Defence Staff, with the change of command taking place on January 14, 2021.

[18] On February 24, 2021, then-Defence Minister Harjit Sajjan announced McDonald had temporarily and voluntarily stepped aside as Chief of the Defence Staff amid investigations on allegations of misconduct.

The Privy Council Office responded that McDonald would remain on leave until the matter was reviewed, and a few days later Eyre was promoted to full general.

[20] In that letter he argued why he should be reappointed as the Chief of the Defence Staff, saying that he had been exonerated and the results of the investigation should be accepted, and that the government’s management of the situation had harmed the Canadian Forces.

[23] The Canadian Forces National Investigation Service also disagreed with McDonald's claim of exoneration in a statement saying that while “no charges [were] laid based on insufficient evidence...This does not mean that the allegation was unfounded.”[21] Naval Lieutenant Heather Macdonald, the supposed victim in the misconduct allegations, described Admiral McDonald's letter as a "public attack on her integrity and said witnesses corroborated her statement to military police".