Second Army HQ took over the faltering offensive in September, and 10th HAG came under its control. The Battles of the Menin Road, Polygon Wood and Broodseinde were highly successful because of the weight of artillery brought to bear on German positions. But as the offensive continued with the Battle of Poelcappelle and First and Second Battles of Passchendaele, the tables were turned: British batteries were clearly observable from the Passchendaele Ridge and were subjected to CB fire, while their own guns sank into the mud and became difficult to aim and fire. 123rd Siege Bty was transferred to 7th HAG within Second Army on 5 October, and then to 71st HAG with Fifth Army on 29 October