[5] Welch was attending officer training school at Camp Zachary Taylor, Kentucky, when the Armistice took place.

[5] Beginning in 1923, Welch was a partner at Hale and Dorr, a Boston law firm, and lived in nearby Walpole, Massachusetts.

[6] On June 9, 1954, the 30th day of the Army–McCarthy hearings, Welch challenged Roy Cohn to provide U.S. Attorney General Herbert Brownell Jr. with McCarthy's list of 130 Communists or subversives in defense plants "before sundown".

McCarthy stepped in and said that if Welch was so concerned about persons aiding the Communist Party, he should check on a man in his Boston law office named Fred Fisher, who had once belonged to the National Lawyers Guild, which Brownell had called "the legal mouthpiece of the Communist Party".

Welch dismissed Fisher's association with the NLG as a youthful indiscretion and attacked McCarthy for naming the young man before a nationwide television audience without prior warning or previous agreement to do so: Until this moment, Senator, I think I have never really gauged your cruelty or your recklessness.

Fred Fisher is a young man who went to the Harvard Law School and came into my firm and is starting what looks to be a brilliant career with us.

Welch's TV performance turned the tide of public and press opinion against McCarthy overnight.

[14][16] After remarrying,[citation needed] he moved to Harwich Port, Massachusetts, on Cape Cod, where he lived until his death.

[17] Sixteen days before his 70th birthday, and fifteen months after the release of Anatomy of a Murder, Welch suffered a heart attack and died on October 6, 1960, at Cape Cod Hospital in Hyannis, Massachusetts.