As President Obama contemplates his second term, he has been talking to historians about another two-term president, Dwight D. Eisenhower.We think of Ike as a great military man, but as president he used his understanding of the military to rein it in. Obama is said to be looking for a low-key way of managing America’s global role while minding Ike’s credo that true national security begins at home with a sound economy, shored up by a careful balance of resources and commitment.How did Eisenhower do it? Once Ike extricated the United States from the Korean War in 1953, he managed to cut the defense budget over his two terms by about a quarter, from about 70 percent of the federal budget to 60 percent. (Today, defense is about 20 percent of federal spending.)Aware from reading Clausewitz and his own experience that small wars have a way of becoming big wars, Eisenhower was determined to keep the United States out of any war.