Glenn Reynolds:

Though people still speak of a decision to go to war as something done to enhance the political position of incumbent presidents, history doesn’t support that. Truman fought in Korea and lost the next election. LBJ had to give up the White House over Vietnam. George H.W. Bush won in Iraq and enjoyed 90% approval ratings but lost the next election anyway. And George W. Bush’s political position certainly doesn’t seem to have benefited from the invasion of Iraq; even in 2004, it was an electoral drag, and things only got worse.
By contrast, presidents who push big social programs generally get a political boost and–because the costs and disasters of social programs are less obvious than the costs of war–there’s seldom any real downside.
So the notion that war is the friend of big government seems questionable to me, based on things that have happened in the past century at least. Rather, it seems that economic crisis, and economic intervention, is the thing to worry about if you want to keep government under control. Which bodes poorly for current times, when the war’s won but the bailouts are coming fast and furious. Eternal vigilance–especially now.