IN THE ANTEBELLUM period, Pittsburgh was a center of popular resistance to slavery. The Republican Party had its founding convention in Pittsburgh on the basis of Free Soil and Protective tariffs. When South Carolina seceded, President Buchanan’s Secretary of War, John Floyd, attempted to move military equipment from many northern arsenals to the South.
The people of Pittsburgh blocked this attempt with massive non-violent direct action. Abraham Lincoln, who won Allegheny County overwhelmingly, visited Pittsburgh shortly after and was greeted with great enthusiasm on his way to his inauguration.
ADDITIONAL perspective can be found here — “‘A vigorous defense’ — Pittsburgh’s forgotten Civil War fortifications” by National Park Service historical interpreter and Civil War scholar *Richard Condon*, published in Civil War Pittsburgh.com — https://www.civilwarpittsburgh.com/po…
“As Robert E. Lee was preparing his invasion of the north in June 1863, citizens across Pennsylvania were in a state of panic. With news spreading of the impending Confederate advance, towns and cities across the Keystone State mirrored a sense of fear and uncertainty. These communities prepared for the worst, and began constructing defensive fortifications at a rapid pace.
“Believed to be viable targets for Confederate forces, the city of Pittsburgh, as well as neighboring Allegheny City and Birmingham, began an aggressive assembly of defensive works. This region of western Pennsylvania served as an industrial and military hub, but also sat within 50 miles of enemy territory along the Pennsylvania/Virginia border. In addition, the Ohio River formed at the confluence of the Allegheny and Monongahela Rivers, and starting in Pittsburgh, served as an open highway to western states and territories.”