I'm writing a research paper, and one of my sources keeps referring to the Nine Years War as the Ten Years War. Is there a valid reason, or is the author just bad at math?

by wherewasmybrain
Bobby_Newmark

What are the sources? We're talking about the war of the Grand Alliance from 1688 to 1697, right? Because the opening moves of the war occurred in 1687, so I can see the author dating the war from that point, especially if he were German.