One charmer--look right--is Frank Vizetelly. He was British, and came from a family heavily invested in both art and newspapers. He drew the Crimean War, and several other armed international uprisings before he decided to come to America and see what he could do here.
His story is, so far, the most convoluted. He began in Washington, D. C., but soon asked to be assigned to an Army. He hung out with the AofP, then wanted to go west with Fremont, et al, but he couldn't!!
He had made a terrible mistake, you see. And this took him off the "A" list really fast.
He drew a sketch of the Union Army as they retreated at First Bull Run, and the London newspapers printed it. This upset General Scott's gout and Cameron's already-dyspeptic nature became absolutely acidic. And the Brits saw our dirty laundry!
He ended up with the Confederates. So there!