During the war Hirst, along with Rhodes and their team-mate Schofield Haigh, worked in a munitions factory in Huddersfield. Hirst and Rhodes were paid by Yorkshire to play in war-time cricket matches on a certain number of Saturdays. Hirst played in the Bradford League, and became known among cricketers for accepting minimal fees from financially struggling clubs. When first-class cricket restarted in 1919, Hirst resumed playing for Yorkshire. In the first match of the season he hit an aggressive unbeaten 180 against MCC, to secure a draw for the county; he followed this with two more centuries in the first two weeks of the season. Although his form later faltered, he played some substantial innings in difficult circumstances and ended the season with 1,441 runs at an average of 38.94. He bowled infrequently, taking 18 wickets at 29.27. During this season, Hirst accepted the position of coach at Eton College. In the last match of the season, at Scarborough, he was given a warm reception by the crowd, who did not expect to see him playing for Yorkshire again. However, he appeared on occasions during the school holidays in the next two seasons, although he did not score any centuries, did not average more than 24 with the bat and took only 21 wickets in total. At the end of the 1921 season Hirst retired as a Yorkshire player, and made what was expected to be his final first-class appearance in a Scarborough Festival match, in which he captained the Players against the Gentlemen. On the last day of the match, Hirst's 50th birthday, he took the final two wickets to secure victory for his side. The crowd gathered outside the pavilion and demanded to see him; he gave a farewell speech, and was moved by the reception given to him.