Answer:
Assuming that you are referring to Lincoln's Second Inaugural Address, here is the answer.
In lines 29-34 of Lincoln's speech, his main premise is that that despite efforts to avoid the Civil war and escalated conflict between both sides of the nation, the opposition was unwilling to be reasonable and resolve conflicts peacefully. Instead, they pushed their own agendas, negotiated, and opposed forming a peaceful resolution. This gradually led to the Civil War and created more of a divide between the north and south of the United States.
The following lines from Lincoln's second inaugural address explain his premise:
" While the inaugural address was being delivered from this place, devoted altogether to saving the Union without war, insurgent agents were in the city seeking to destroy it without war--seeking to dissolve the Union, and divide effects, by negotiation. Both parties deprecated war; but one of them would make war rather than let the nation survive; and the other would accept war rather than let it perish. And the war came"