Although most soldiers in the U.S. Civil War were between 18 and 39, an estimated 20% of the soldiers were underage -- and thousands of those children were under the age of 15. John Lincoln Clem was one of the most extreme examples of this phenomenon, and remains one of the most well-known today. He joined up with the Union when he was only eleven years old, surviving multiple conflicts and living to the ripe old age of 85. But how did he feel about the practice of allowing children into battle? The answer might surprise you.