 Following the explosions , the Allied advance was virtually unopposed as the Germans were too stunned and demoralised to put up much resistance . However , not everything went the Australians ' way . The 3rd Division , under Major General John Monash , suffered heavy casualties when they were shelled by phosgene gas and shrapnel shells while moving towards the line of departure , nevertheless the division still managed to get into position for the start of the attack . Strong German counterattacks were launched the next day , once again supported by concentrated artillery fire ; however , the advance was able to continue on through the mess of concrete blockhouses the Germans had erected and continued on until all the objectives had been taken . Australian casualties amounted to nearly 6 @,@ 800 men . On 2 July 1917 , Major General Holmes was mortally wounded by a German shellburst while surveying the Messines battlefield with the Premier of New South Wales , William Holman . 
