Croak was born in Little Bay in Newfoundland, on May 18, 1892 to James and Cecelia Croak. The family moved to Glace Bay, Nova Scotia when Croak was two years old. He attended school there and then, at the age of 14, began work as a coal miner.
In 1915, Croak enlisted in the Canadian Army and volunteered for service abroad with the Canadian Expeditionary Force. Posted to the 55th Battalion as a private, he embarked for Europe in November 1915. He soon transferred to the 13th Battalion, which was serving on the Western Front as part of 3rd Brigade, 1st Canadian Division. Through 1917 and the early part of 1918, Croak participated in several engagements as part of 13th Battalion; these included the Battles of Vimy Ridge, Hill 70 and Passchendaele. On 8 August 1918, the opening day of the Battle of Amiens, and the beginning of the Hundred Days Offensive, the 3rd Brigade, accompanied by a battalion of tanks, was at the forefront of the 1st Division's advance. The 13th Battalion became held up by machine gun posts in the vicinity of Hangard Wood. Croak attacked a machine gun post and took several prisoners whom he escorted to his company headquarters. Ignoring instructions to seek medical treatment for a wound to his arm, he carried out an attack on another machine gun post nearby. He was wounded again, this time fatally, in the act, and died that same day. He was recognised for his actions with an award of the Victoria Cross. The VC, instituted in 1856, was the highest award for valour that could be bestowed on a soldier of the British Empire. The citation for Croak's VC read: Croak is buried at Hangard Wood British Cemetery, which is located 12 miles south west of Albert. His VC, the first to be awarded to a soldier born in Newfoundland, was presented to his mother at Government House in Halifax by MacCallum Grant, the Lieutenant Governor of Nova Scotia, on 23 November 1918. In Glace Bay, where Croak grew up, there is both a school and a Royal Canadian Legion named in his honor. There is also a park, located on the site of his former workplace, the Dominion No. 2 Colliery, named for him as well. In 1992, the park was the scene of the unveiling of a memorial plaque, made of Cape Breton rock, to Croak.
