Has any handgun ever actually decided a war? I doubt it. Usually it gets decided by rifles, machine guns, artillery, logistics, air power, naval power, quality of generals, etc.
Undoubtably true. Nevertheless, a handgun is...
1st: the most "personal" kind of firearm a soldier may carry and
2nd: the one his live may depend on when things go wrong and
3rd: moreover, also the kind of weapon most interesting for most civilian shooters
Thus, the "military handgun" issue will always weight in more than its actual value on a strategic level may imply. And its still interesting discussing it, btw.