Jack Dwyer was born at Lovett (now Cygnet) Tasmania. He enlisted in early 1915 and served on Gallipoli with the 15th Battalion. In 1916 he went to France with the 4th Machine Gun Company.

Next year on 26 September 1917, during the battle of Polygon Wood (Zonnebeke, Belgium), Dwyer's Vickers machine-gun team came under fire until he rushed his gun forward, and at point-blank range put the enemy gun out of action. He then took both weapons and helped repulse a German counter-attack. Later, after his Vickers was blown up by shellfire, he led his team back through the enemy barrage to secure another and then bring it into action. At all times, he showed "contempt of danger, cheerfulness and courage".

Dwyer was commissioned in May 1918 and returned to Australia five months later. Back in Tasmania, he became active in local affairs and politics. He established a sawmilling business at New Norfolk. In 1931 he entered state parliament and eventually held several important offices, including that of deputy premier.

Dwyer received the Victoria Cross, service medals for the First World War and coronation medals for King George VI and Queen Elizabeth II.