half of the union army was made up of Immigrants, cannon fodder is a bit strong.
Melting Pot Soldiers: The Union's Ethnic Regiments North's Civil War: Amazon.co.uk: William Burton: Books
1,000,000 45.4 Native-born white Americans.
516,000 23.4 Germans; about 216,000 were born in Germany.
210,000 9.5 African American. Half were freedmen who lived in the North, and half were ex-slaves from the South. They served under white officers in more than 160 "colored" regiments and in Federal regiments organized as the United States Colored Troops
200,000 9.1 Irish.
90,000 4.1 Dutch.
50,000 2.3 Canadian.
50,000 2.3 Born in England.
40,000 1.8 French or French Canadian. About half were born in the United States of America, the other half in Quebec.
20,000 0.9 Scandinavian (Norwegian, Swedish, Finnish, and Danish).
7,000 Italian
7,000 Jewish
6,000 Mexican
5,000 Polish
4,000 Native Americans