Who were the foreign soldiers in American Civil War?

Mostly Irish and German immigrants, fighting for the north almost exclusively. There were a few Irish from New Orleans in the southern service. And of course there were a handful scattered around who had been born in other countries in the armies of both sides, and a few adventure seekers on both sides who came for the chance to experience the biggest war then available on the planet. Among these Soldiers of Fortune were Heros von Borcke, of Prussia (Germany), who fought with the southern cavalry as a staff officer with Jeb Stuart, and who wrote a war memoir. Colonel Freemantle, of Her Majesty's Coldstream Guards, later Field Marshal and CIGS (head of the British Army) came through the blockade to be an observer with the Rebel Army, as professional officers like to do when there's a war on their nation isn't involved in, to keep abreast of developments in their trade. Freemantle was at Gettysburg, and also wrote an often-quoted book.