The 50th Battalion saw its first serious action during the Battle of Mouquet Farm in mid-August 1916. During the battle, the 50th Battalion suffered 414 casualties, largely from the heavy German artillery bombardment. On 14 August, Jensen was hit in the left shoulder by a piece of shrapnel. He was evacuated to the UK and admitted to Graylingwell War Hospital in Chichester, West Sussex. While in the UK, he was charged with more disciplinary infractions in September, December and January, on one occasion being sentenced to 28 days field punishment for missing the troop train to return to France, and on another serving 12 days detention for being absent without leave. He did not rejoin his unit until 28 January 1917.