There aren't that many liberals in the military because they don't respect military service. They would rather surrender than fight. The only Corps they respect is the Peace Corps.
My wife and I are Jewish. She tells me that I am one of only two Jewish man she knows who volunteered for the military. I have only one other on my side of the family*. Most of my generation of fellow American Jews are, frankly, self-centered pricks.
* does not include my Jewish friends who joined the Guard to avoid active duty during Vietnam