I read this as part of The Time Traveller’s Almanac, edited by Ann and Jeff VanderMeer.
Elizabeth Hazel and Lewis Alisdair are time travellers. It seems Lewis has travelled with the mysterious John a few times previously, but that Elizabeth is a new-comer to the endeavour. The book opens as the pair find themselves NOT where they are meant to be. Instead of at the Crystal Palace in London, 1851, they find themselves in bushes. And soon after, gunfire surrounds them. They attempt to escape the apparent battle by wading downriver and then land up in another stand of trees, where another time traveller (not John) finds them. They discover that they’re in Virginia in the first week of May, 1864.
I think I missed something in this story. It was a nice enough read, insofar as gun battles and raging fires go, but… a few connections seem to be missing. Yes, there was no mention of the method of time travel. I realise that the battle in question is related to the American Civil War. But that’s about as far as I get. I clearly just don’t get it.