The military isn't as conservative as many people think -- it's actually a pretty good representation of the voting preferences of the public at large.

"It is true that the upper echelons of the military tilt right," but "only 32 percent of the Army’s enlisted soldiers consider themselves conservative, while 23 percent identify as liberal and the remaining 45 percent are self-described moderates." [1]

For reference, the officer corps of the military only makes up ~16% of the total number of service members.[2]

[1] http://andrewgelman.com/2009/05/05/how_soldiers_re/

[2] http://en.wikipedia.org/wiki/United_States_Armed_Forces#Pers...