In preparation for an attack on the Hindenburg Line at Bullecourt, the 1st Australian Brigade—of which the 1st Battalion was part—was attached to the 2nd Australian Division. The attack commenced in the morning of 3 May 1917, with the 2nd Division lined up in conjunction with thirteen other divisions. Despite some progress made early in the attack, the Australian forces were soon held up by strong opposition, and in the evening the 1st Battalion was entrenched in the old German line known as 'OG1'. Three of the battalion's companies occupied the line, while a fourth was placed in reserve. Their position was such that they occupied a wedge into the German line, while two flanks were in German held territory.
From the initial attack, only the Canadians on the extreme right and the 3rd Australian Brigade on the extreme left were able to capture and hold their set objectives. Over the course of the next three days, severe fighting took place and further troops were drawn in to hold and extend the gains of 3 May. On 6 May, the Germans launched a counter-attack which forced the 3rd Brigade to withdraw from their trenches; it was during this engagement that Howell was to perform the act which was to earn him the Victoria Cross.
At 06:00, Howell, who was in charge of a post to the right of the line, noticed the battalion on the right flank was being forced out of its trench and was beginning to retire. Immediately alerting battalion headquarters, Captain Alexander MacKenzie—who had assumed temporary command of the battalion—hurriedly organised a group of non-combatant soldiers from headquarters together with several signallers to form a defensive line along a road bank in order to fend off the expected German advance. A fierce bombing and grenade fight soon ensued, with both sides suffering heavy casualties. Fearing the Germans would outflank his battalion, Howell climbed onto the top of the parapet and began running along the trench line throwing bombs down on the Germans, all the while being subject to heavy rifle and bomb attack. Forcing the Germans back along the trench, Howell was supported by Lieutenant Thomas Richards who followed him along the trench firing bursts from his Lewis Gun. Soon exhausting his supply of bombs, Howell began to attack with his bayonet until he fell into the trench wounded. Howell had been hit in both legs by machine gun fire, and when he was brought into the clearing station some hours later, it was discovered he had suffered at least twenty-eight separate wounds. Due to his actions, the ground which had been lost was soon retaken, and the German attack was later repulsed.