Foreign enlistment in the American Civil War (1861–1865) reflected the conflict's international significance among both governments and their citizenry. Diplomatic and popular interest were aroused by the United States' status as a nascent power at the time, and by the war's central cause being the globally divisive issue of slavery.[2] Consequently, many men enlisted from abroad and among immigrant communities in the U.S.[3] When hostilities first broke out, roughly 13% of Americans were foreign-born, the vast majority concentrated in northern cities; subsequently, foreign enlistment largely favored the Union, which was also far more successful at attracting volunteers.
Roughly a quarter to a third of the Union Army was foreign-born, or 543,000–625,000 out of 2 million troops; an additional 18% had at least one parent born abroad, meaning close to half the Northern army had some recent foreign origin.[2] By contrast, only several thousand foreigners served with the Confederacy, comprising just 5% of its armed forces.[4] The significant manpower advantage to Union forces proved decisive to its victory,[2] with some historians claiming the North otherwise would not have prevailed.[5][2]
Reflecting the influx of immigrants leading up to the war, the largest foreign contingents on either side were German, Irish, and British (including English, Scottish and Welsh).[6] Most other foreign recruits were from Canada and the rest of Europe, particularly Poland, France, Italy, and Scandinavia;[5] smaller numbers came from China, Mexico, Hawaii, and various Native American tribes.[7] Several high-ranking political and military leaders in both the Union and Confederacy were of foreign or immigrant background.
Like American citizens, foreigners and immigrants fought in the war for various reasons; many were motivated by an ideological opposition to slavery, others by loyalty to their adopted homeland, and still others sought economic opportunity.[2] Regardless of their motives and origins, most foreign soldiers reportedly served with as much loyalty and distinction as native-born Americans.[5] Nevertheless, many were subject to the wider nativist sentiments of American society, as well as to prejudices against their particular ethnicity, faith, or nationality.[8] Some in the Union downplayed immigrant contributions, partly in response to Confederate propaganda directed at both Northern and foreign audiences that claimed the Union was relying heavily on "foreign mercenaries" and "refuse" to serve as cannon fodder.