It's highly unlikely that any of them are alive let alone able to fight, but that hasn't stopped the families of more than 14,000 American men born between 1893 and 1897 receiving orders to register for the military draft.
Last week baffled relatives began receiving the notices from the The Selective Service System, an independent agency of the US government that keeps information on those who might be eligible military conscription.
Chuck Huey, 73, told the Harlan Daily Enterprise newspaper that he received one of the letters for his grandfather Bert, a First World War veteran who died aged 100 in 1995.
He said: “If he was here, yeah, he would probably laugh and say, ‘Yeah, I’ll go.’ He was that kind of guy,”
He added: “Maybe the Selective Service can come for a visit and I will take them the cemetery and introduce them to my grandfather at his grave site.”
The agency realised the error when it began receiving calls from bewildered families last week. An apology on its website blamed a "computer error" for the 14,215 letters sent out.