What was the name of the speech given by Abraham Lincoln when accepting the Republican nomination for the Illinois senate seat, emphasizing the division between slave and free states?

The speech given by Abraham Lincoln when accepting the Republican nomination for the Illinois senate seat is known as the House Divided Speech. In this address, delivered on June 16, 1858, Lincoln famously stated, “A house divided against itself cannot stand,” highlighting the growing tensions and divisions between slave and free states in the United States. He articulated his belief that the nation could not endure permanently half slave and half free. This speech marked a significant moment in the political landscape of the time, as it set the stage for his debates with Senator Stephen A. Douglas and underscored the importance of the slavery issue leading up to the Civil War.

The other speech options listed are notable in their own right but serve different contexts; the Emancipation Speech focuses on the abolition of slavery, the Gettysburg Address commemorates the fallen during the Civil War, and the Second Inaugural Address reflects Lincoln's thoughts on the war and reconciliation towards the end of his presidency. Each of these speeches addressed different aspects of the crisis and the nation’s challenges, but the House Divided Speech specifically emphasizes the central theme of division between slave and free states at the heart of Lincoln's political narrative at that time.