On Oct. 26, 1918, a U.S. soldier stationed in Europe sat down with a gray pencil to compose a letter to his wife, Clara. It arrived eventually, minus a word. “We are billeted in a little [redacted] town,” wrote John Kennelly, a private first class. His descriptor was erased by a military censor. It was a simple, surgical excision on behalf of a powerful government, which had love letters to deliver but secrets to keep.