https://millercenter.org/president/abraham-lincoln/key-events
The relevant facts are that this 75k troops called up by the 16th president, Lincoln, were in response to an "insurrection" at Fort Sumter where NOBODY was killed. The 75k were trained by McClellan
(The Democratic Party Presidential Candidate Opponent of Lincoln in the 1864 election)
Jefferson Davis, former Secretary of War for the USA under a previous administration,
14th President Franklin Pierce. Davis at that time commissioned the Topographical Engineers of the Army Corps of Engineers to Map out a plan for 5 Transcontinental Railroad Routes. He ordered McLellan to survey parts of the Western North/South route from San Diego to Tacoma, and the Northern Route from Tacoma to Minneapolis. (The final one of the five to eventually be completed)
McLellan had a little help from Frederick Lander to survey multiple sections for Jefferson Davis as USA Seceretary of War. All 5 of these routes commissioned by Davis, would be built by the Union in the Aftermath of the U.S. Civil War.
McClellan was a President of a Railroad Company at the time Lincoln asked him to re-enlist and become General and leading trainer of 75k troops in his state of Ohio. McLellan was Lincoln's 2nd choice, as Honest Abe offered the job of General initially to the U.S. Marines leader at 1859 Harpers Ferry, a Virginian U.S. Officer by the name of Lee.
Lee, a fourth generation Virginian whose wife was the great grandaughter of George Washington's wife, Martha Custis, The First, first lady of the USA
Lee, declined Lincoln's offer, for he simply could not raise arms against his family's
Commonwealth of Virginia.
After 6 weeks of training, Lincoln and McLellan went on the Offensive:
-McLellan sent 3,000 troops from Ohio,
1,600 transported by Railroad Train from the North, 1,400 from the West in
a double envelopment, or pincer movement onto an unsuspecting town of 400 residents in Virginia
Assembled on the outskirts on Private Property of U.S. Citizens,
Raided the town, broke up their printing press, and resulting in amputations, injuries and 30 deaths.
-That same day, Stephen Douglas a narrow loser to Lincoln in the recent election, mysteriously up and died.
-Two nights prior, troops also ordered by McLellan, raided Fairfax County Courthouse, acquired some files and ransacked the place.
Game On.
By the time Honest Abe was through, Four Years later, 600,000 Americans lay dead.
Yes Slavery and it's Abolishment was The MAIN ISSUE.