“The good guys don’t employ child soldiers.”
Virgil Mounts of Kentucky was 15 when he died on Omaha beach as a medic in the 6th Naval Beach Battalion.
Robert Johns of Portsmouth, UK was 16 when he parachuted into France behind Sword beach. He was killed at Le Mesnil, France on 7/23/44.
Given the time needed for basic training, advanced training and transport Mounts is estimated to have been 13 when he enlisted.
Johns was 14 when he ran away from home and joined the army.
Joseph Plumb Martin was 16 when he joined the Continental army. He kept a daily journal that was discovered amongst family belongings in the 1950’s. Historians have called the journal a “gold mine”. It has been extensively quoted in documentaries.
In the pre-modern British army the officers were well connected with either Parliament or the crown. It was a common practice for them to take their 10-12 year old sons along as drummers or messengers. Many of those child soldiers died before their 14th birthdays.
All the people you mention fraudulently enlisted in the US military by lying about their age.