In early 1917, the 4th Light Horse Brigade was reconstituted at Ferry Post on 13 February under the command of Brigadier General John Meredith. Assigned to the brigade along with the 4th and 11th Light Horse Regiments, the regiment's time of operating as a detached unit came to an end; they officially readopted the designation of 12th Light Horse Regiment at this time. For the next month they undertook training exercises before joining the advance into Palestine, while some men from the regiment were also detached to join Dunsterforce in Persia. In April, the regiment took part in the Second Battle of Gaza. Assigned the task of attacking the Atawineh Redoubt early in the morning of 19 April, the regiment dismounted about from it and advanced on foot. Initially, they made good progress and captured a ridge about from their objective without even firing a shot. As the defensive fire grew more intense, the men were forced to the ground and began fire and movement drills. Spread thinly across a front with just 500 men, the 12th was dangerously exposed as machine-gun fire began to inflict casualties, checking the Australians' advance. Nevertheless, the regiment held its position throughout the day until being withdrawn to a nearby hill that night, by which time it had suffered more than 30 percent casualties. These included the commanding officer, McIntosh, who was gravely wounded and subsequently died of his wounds. He was replaced by the second-in-command, Major Donald Cameron, who was later promoted to lieutenant colonel.