Corporal Leonard Allen enlisted in the Australian Regular Army on 20 November 1967 and was posted to 5th Battalion, The Royal Australian Regiment in May 1968. He arrived in South Vietnam in February 1969 and is serving as a Section Commander in 5 Platoon, B Company.

In August 1969, Corporal Allen's Platoon had several contacts with superior size enemy forces entrenched in bunkers. During one contact while 5 Platoon was protecting B Company Headquarters, the enemy launched a counter attack against the B Company element. Corporal Allen took over a machine gun and quickly moved forward to bring effective fire to bear on the enemy. Despite intense enemy rocket and machine gun fire that was directed against his position, he maintained an accurate volume of fire which stopped the enemy and forced them to withdraw with casualties.

Throughout 1969, Corporal Allen has been in many contacts with enemy forces and has shown himself at all times to be a fearless leader who displayed a continuous disregard for his own safety. His outstanding actions reflect great credit on himself and The Royal Australian Regiment.