1/1st Highland Hvy Bty moved to 48th HAG on 16 May 1917, to 3rd HAG on 29 May, to 73rd on 26 June, and then to 28th HAG in Fourth Army on 7 July. Fourth Army was at the time stationed on the Flanders coast awaiting a breakthrough at Ypres that never came. Eventually, the battery was transferred on 11 September to 35th HAG with Second Army, which was taking over the direction of the faltering offensive. 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. 1/1st Highland Hvy Bty had been moved to 28th HAG on 17 October, then on 27 October, as the fighting at Passchendaele ground on, it was transferred away to 83rd HAG to the quiet sector of First Army's front.