Gaby, in command of a company, moved with his unit to the east of Villers-Bretonneux towards Card Copse, where unbroken wire entanglements were encountered. Heavy fire from Germans covering a gap in the wire pinned down the Australians. Gaby found a gap in the wire and, single-handedly, approached an enemy strong point while machine gun and rifle fire poured from it. He ran along the parapet, emptied his revolver into the garrison, drove the crews from their machine guns and forced fifty of the enemy to surrender. This resulted in the capture of four machine guns. He then reorganised his company and consolidated the objective. Three days later he was killed instantly by sniper fire.