Ha!
It's a long, long story, beginning before the Civil War, running through the First World War and well beyond.
Right "now" one of my great-grandfathers is a 20 year old unmarried farmer living with his family near Quincy, Illinois.
They are fresh off the boat from Europe and speak very little, if any, English.
They are naturally abolitionists, but they have no "dog in the fight" and indeed, it's said they left their Old Country precisely to dodge the draft into yet another senseless European war.
So my great grandfather and his younger brother will not rush off to war, but will eventually be drawn to volunteer, at just around the time of Lincoln's Emancipation Proclamation.
Like I said, it's a long story... ! ;-)
I've got time and patience.
I just wish I knew more about my own family history during this era. The earliest Deardorffs I have records for were in Lancaster Co. PA in the late 18th century. From there they gradually moved west, first to Ohio, then Indiana, up by the lake, until by the end of the war they were being born, married and buried in Kansas. In the 1860s they must have been scattered all over the midwest. or as they call it "now," the northwest. So, unless they were all determined pacifists, I probably have several ancestors who served in the Union army. My Mormon aunt who collected the genealogy apparently wasn't interested in that aspect of family history, for she left me not a word about it.