On recovering his health, in April 1916 Forsyth was posted to the NZEF base at Étaples before rejoining the 3rd Field Company, now serving on the Western Front in support of the New Zealand Division's 3rd Infantry Brigade. Later in the year he spent a period of leave in the United Kingdom and struck up a relationship with a Glaswegian, Mary, who he soon married. From mid-September 1916, during the New Zealand Division's involvement in the Battle of the Somme, Forsyth's company was heavily engaged in construction of roads and strongpoints and then from early October was stationed in Armentieres, now attached to the 2nd Infantry Brigade. The 3rd Field Company worked to improve the defences of the sector, which included the construction of several small dams to direct excess water towards the German trenches.