Back then, States had much more meaning than they do now. Robert E. Lee was very much against secession, yet wouldn't go against his State. George Thomas, a fellow Virginian, decided that our country was greater than the State (it didn't hurt that he married a lady from New York State and despised slavery).
The Brown raid was very important, but the previous things I wrote about were the main catalysts.
” John Brown was cold-blooded for the Abolitionists, Bloody Bill Anderson was a killer for the Confederates.”
There is at least one significant difference between the two and that’s timing. Brown’s murderous career was before the war and had a role in igniting it. Anderson was a guerilla in the middle of the war.