Throughout the spring of 1918, the 18th Battalion was involved in operations to repel the German offensive. Maxwell took part in these actions until he was granted leave and went back to England on 17 July. He returned to France and rejoined the 18th Battalion on 1 August, before taking part in the Battle of Amiens where he was to earn a Bar to his Military Cross. On 9 August, the battalion was preparing to attack near Rainecourt. Maxwell took command of the company after all of its other officers became casualties. Under his leadership, the company was able to attack on time, despite being subjected to heavy fire. A tank that preceded the advance immediately became the object of enemy fire and was knocked out by a 77 mm gun. Maxwell, who was in close proximity, rushed over and opened the hatch, allowing the crew to escape. After escorting the tank commander to safety, Maxwell returned to lead the company in the attack, which succeeded in reaching and consolidating their objective. The award of the bar was published in a supplement to the "London Gazette" on 1 February 1919.