A person who now advocates war but who once took special measures to avoid military service. Also: chicken-hawk, chickenhawk.
Well, it looks like the "chicken-hawks" are at it again. These people who were too chicken to go to war (or even serve in the military) become middle-aged hawks looking for an opportunity to send others to kill and be killed.
Peter Lorenzo, "Chicken hawks," Sacramento Bee, March 31, 2002
In England during World War I, as thousands were dying pointlessly in the trenches, pretty girls went around handing white feathers a symbol of cowardice to men who weren't in uniform. The one group currently being handed white feathers who may deserve them are the so-called "war wimps" or "chicken hawks" prominent Americans helping to spread war fever today who avoided service during Vietnam.
"No white feather, please," The New Republic, June 16, 1986
There's also an earlier war-related sense that has a slightly different meaning: Someone who willingly goes to war, but who is also afraid of combat. This sense appears to have been coined by the writer Robert Mason in his 1983 Vietnam memoir, Chickenhawk:
It is to combat that Bob Mason is always drawn, no matter how frightened he feels (which is why he is both ''chicken'' and a ''hawk,'' therefore a ''chickenhawk'').
Christopher Lehmann-Haupt, "Chickenhawk," The New York Times, August 4, 1983
The red-tail hawk is known in certain parts of the U.S. as a chicken hawk. And although many people of a certain age would be hard-pressed to tell you what a chicken hawk looks like, they know the term well having been brought up watching Foghorn Leghorn cartoons, many of which featured a young chicken hawk named Henry. (Foghorn Leghorn was a rooster and he was many times larger than Henry, but that didn't stop the confident but confused youngster: "You're a chicken and I'm a chicken hawk; are you coming quietly or do I have to muss you up?")
A different, though still possibly overlapping, segment of the population will be familiar with another sense of the phrase chicken hawk: A gay man who prefers adolescent sexual partners. (This term has also been used for a straight man who seeks adolescent girls.)
That sense dates to 1965, so it's much older than the sense used in today's phrase.