How many soldiers leave their families to go to war?

All the ones who have families that aren't all in the military. The exact number varies from war to war - Iraq had more than Afghanistan which had more than World War II. (Right now you're thinking, "but more troops participated in World War II!" You are very correct, but remember: World War II was fought by draftees straight out of high school. The number of married troops in that conflict was relatively low. Iraq and Afghanistan were fought by professional soldiers, and a lot of them are married.)