Hart was promoted to lieutenant colonel while recovering from his wounds in England. He returned to the Dardanelles in September 1915 as commander of the Wellington Battalion, Malone having been killed in action in early August during the Battle of Chunuk Bair. The battalion had been decimated during the battle but remained in the line manning positions at 'The Apex', a knoll near Chunuk Bair. Along with the rest of the New Zealand Infantry Brigade, the battalion was transferred to the Greek island of Lemnos on 14 September for a period of rest and recuperation while it was also being built up with reinforcements from New Zealand. While on Lemnos, Hart commanded the brigade for a 12-day period when its nominal commander, Brigadier General Francis Earl Johnston, was hospitalised.