[CaptainHaplo]

Most data available indicates that when it comes to US military members, former members and retirees, the split is about 60% / 15% when asked to identify themselves as Republican / Democrat. Most of this data comes from polled Officers, though anecdotal data (always suspect) puts the number for enlisted at around 50/20.

Overall, the reasoning is fairly straightforward. On average, democrats are seen as "weak" on military spending and related issues. I am not saying this is an accurate view, or innaccurate - only how it is generally viewed. It is statements such as "I voted for it before I voted against it" by Sen. Kerry, as well as historical party positions, that lead to this perspective. Republicans however are seen as willing to spend on average more for the military. Again, historical party stances and votes, as well as individual leaders (such as Reagan) demonstrate why this view is generally accepted.

Just like any other group, if a particular party is more apt to give you a bigger slice of the pie, you are more likely to support them. This is the same logic used by those who pander to illegals, or lobbyists.