Answer:
While slavery was the major issue separating the North and South, it was not slavery itself that sparked the conflict. The South wanted to secede from the Union, and the North refused. While President Abraham Lincoln personally opposed slavery, he recognized that it was legal under the U.S. Constitution at the time. He also recognized that few in the North were ready to go to war to free the slaves. For Lincoln and the northern majority, preservation of the Union was the foremost goal.
It has to do with spirituality, symbolism, and tradition. It symbolizes putting a part of four peoples spirit into woodcut. It is a tradition for all four people to put their spirit into it.
The Japanese woodcut prints were created by a collaboration between four people: an artist, a publisher, a printer and a block cutter.
This print is known as ukiyo-e prints. It involved the division of labor as the Printer printed with water inks, the Publisher financed, the block cutter carved blocks and the artist drew the colors.