With no explanation, label text_A→text_B with either "DON'T KNOW", "NO" or "YES".
text_A: In December 1861, Lincoln sent his first annual message to Congress (the State of the Union Address, but then typically given in writing and referred to by a different name). In it he praised the free labor system, as respecting human rights over property rights; he endorsed legislation to address the status of contraband slaves and slaves in loyal states, possibly through buying their freedom with federal taxes, and also the funding of strictly voluntary colonization efforts. In January 1862, Thaddeus Stevens, the Republican leader in the House, called for total war against the rebellion to include emancipation of slaves, arguing that emancipation, by forcing the loss of enslaved labor, would ruin the rebel economy. On March 13, 1862, Congress approved a "Law Enacting an Additional Article of War", which stated that from that point onward it was forbidden for Union Army officers to return fugitive slaves to their owners. Pursuant to a law signed by Lincoln, slavery was abolished in the District of Columbia on April 16, 1862, and owners were compensated.
text_B: When referring to Lincoln's letter to Congress, would a congressman simply refer to it as a message, rather than the State of the Union?
YES.