MacDonald stood for Parliament in the 1921 Woolwich East by-election and lost. His opponent, Captain Robert Gee, had been awarded the Victoria Cross at Cambrai; MacDonald tried to counter this by having ex-soldiers appear on his platforms. MacDonald also promised to pressure the government into converting the Woolwich Arsenal to civilian use. Horatio Bottomley intervened in the by-election, opposing MacDonald's election because of his anti-war record. Bottomley's influence may have been decisive in MacDonald's failure to be elected as there were under 700 votes difference between Gee and MacDonald.