In March 1916, Leak and the rest of his battalion sailed for France and the Western Front. They spent several weeks in a quiet sector of the line near Armentières, before deploying south to the Somme river valley, where they experienced their first fighting in France. On 1July, the Battle of the Somme commenced. This mainly British offensive involved attacks against German trench systems on either side of the Somme. British troops pushed slowly forward towards Bapaume until they were just short of the village of Pozières, at which time the Australian 1st Division entered the fray in the Battle of Pozières. The German positions at Pozières were known as the "Old German" (OG) trenchesOG1 and OG2. The Australians launched a preliminary operation on 22 July, but were repulsed. The following day, the division attacked again, this time with the 1st Brigade on the left, and the 3rd Brigade on the right. Leak's battalion was allocated a sector on the far right flank of the divisional attack. The troops captured the first objective, but were held up by a German position where OG1 met "Pozières Trench".