It was decided by Field Marshal Douglas Haig that the Fourth Army's Australian Corps would lead the Battle of St. Quentin Canal . However, due to the Corps depleted nature, which was a result of fighting almost continuously, it would be reinforced by the 27th and 30th divisions, which resulted in II Corps being temporarily reassigned under Australian command. This great Somme "push", which lasted from 24 September to 1 October, saw the 27th engaged in severe fighting along the Saint Quentin Canal Tunnel—one of the out-lying strong points of the Hindenburg Line. At the conclusion of the first phase of the battle, and following heavy losses, the 27th was placed into reserve for rest and recuperation. Six days later, the division was sent back into the line, moving steadily toward Busigny whilst chasing the retreating Germans. These operations were supported by Australian Artillery until 9 October, when British artillery units began supporting the division's operations. As a result of these offensives by the Australian, British and US forces, the Hindenburg's Main Line was penetrated.