"We surrender! Just keep that sidekick away from us!"
The kid sidekicks of Golden Age comics are a genre convention that seems indefensible today. A grown man putting on a costume and going out to fight criminals (sometimes with super-powers but most often with just fists) can be accepted as the basic premise. But for the same guy to bring along a minor (usually shown as about fourteen or fifteen, often clearly younger)into mortal danger is hard to defend. Despite all the training and preparation, taking a kid up against armed gangsters seems like an unacceptable practice from today's viewpoint.
Except for Bucky. Say he was fifteen when he first became Captain America's partner. The truth is that an awful lot of underage boys got into the armed forces in WW II. There was intense patriotic fervor, and computer background checks were not even dreamed of. It was much easier to fake an ID back then, and the demand for manpower led to many recruits getting only a cursory check before being put into training. "If you can walk up to the draft board under your own steam, they'll take you."Not having the Super-Soldier serum or an indestructible shield, Bucky was a tough egg anyway. Did he grow up in the slums, fighting among street gangs? Once he put on that costume and went up against Japanese and German troops (not to mention various mad scientists, masked villains, monsters and fiends), Bucky had no reluctance against using a little equalizer.