Wallach's club rugby career was with the Eastern Suburbs RUFC in Sydney where he played as a lock. He made eight state representative appearances for New South Wales and appeared on five occasions between 1913 and 1914 for Australia.
Military career
Wallach was commissioned as a Lieutenant in the 19th Battalion, 5th Brigade, of the 2nd Division raised in March 1915, disembarking in June 1915. After training in Egypt, the battalion landed at Anzac Cove on 21 August 1915, and following that took part in the attack on Battle of Hill 60. Wallach wrote a letter home from Gallipoli which was published in the sporting paper The Referee. He described hearing of the deaths of his Eastern Suburbs clubmates Harold George and Fred Thompson from William Tasker another rugby contemporary who saw Gallipoli action and who like Wallach, would die on the Western Front."We arrived at Heliopolis about three weeks ago. We have been in some pretty solid work, but expect to go into the real stuff next week. All the rugby union men are well here, from the Major down to the privates. Twit Tasker told me how Harold George died the death of deaths – a hero's – never beaten till the whistle went". Clarrie kept a diary at Gallipoli which is referred to by Carlyon for its glib style, e.g."Nothing of note, two skittled by shrapnel"
The attack, supported by a barrage was to go in at 4.55 am on 7 April, a cold and rainy night. Something went wrong on Wallach's front and no barrage fell ahead of him. He nonetheless led his men across 400 yards of open country toward the wood. German machine gunners untouched by shells, opened up. By the time the company reached the edge of the wood one man in four had been hit. Wallach fell with wounds to both knees. Storkey, following seventy-five yards behind Wallach, took command. He pushed into undergrowth with eleven men trying to get behind the Germans. They successfully surprised an enemy position containing 80 to 100 men, driving them out, killing and wounding about 30 and capturing three officers, 50 men, and one machine gun. Wallach had suffered a compound fracture of his left leg. Gas gangrene set in and doctors amputated the limb. His temperature soared to 105 degrees. He was given a blood transfusion to try to save the other leg but eventually it had to come off too. Wallach began to weaken: the shock was too great. He died on 22 April, aged twenty-eight. He is buried in the Etretat Churchyard Extension in Étretat, France.
