He volunteered for the United States Army Air Forces during World War II and served as a B-24 Liberator bomber pilot in the Fifteenth Air Force, flying 35 missions over enemy territory from bases in North Africa and later Italy, often against heavy anti-aircraft artillery. McGovern was awarded the Distinguished Flying Cross for saving his crew by crash landing his damaged bomber on a small Mediterranean island.
McGovern was outspoken in his criticism of the Senate's "war hawks"
. During Senate floor debate in September 1970, he assailed his colleagues for not supporting an amendment that he had cosponsored with Senator Mark Hatfield (R-Oregon) calling for a complete withdrawal of troops from Vietnam
"Every Senator in this chamber is partly responsible for sending 50,000 young Americans to an early grave... This chamber reeks of blood... it does not take any courage at all
for a Congressman or a Senator or a President to wrap himself in the flag and say we are staying in Viet Nam, because it is not our blood that is being shed
The McGovern Commission changes to the convention rules marginalized the influence of establishment Democratic figures
(some of whom had lost the nomination to McGovern). Many refused to support him, with some switching their support to the incumbent President Richard Nixon through a campaign effort called "Democrats for Nixon". In addition, McGovern was repeatedly attacked by associates of Nixon, who used an array of "dirty tricks" and illegal tactics during the campaign
In the general election, the McGovern/Shriver ticket suffered a 60%-38% defeat to Nixon — at the time, the second biggest landslide in American history, with Electoral College totals of 520 to 17.