300,000 Person Country : 4700-man Army. Meet 1960s Luxembourg
At its height during the 1960s, the Luxembourg Army consisted of a rather large – proportionally – 4,700-man brigade stocked through universal conscription. This was reformed in 1967 though when the armed forces underwent a significant downsizing with the abandonment of the unpopular draft, following which the Army numbered a single under-strength battalion, the 1st Luxembourg Light Infantry, of 720 men, supplemented with a Gendarmerie and reserves. Following this reform, they became the
only army in continental Europe to be an all-volunteer force.
For reference, if the US used this same model today, it would have a 4.7-million-person army, which is about nine times what we have currently.