What new challenge does Lincoln face that his fifteen predecessors have not?

In 1864, Lincoln faced many challenges to his presidency. The war was now in its fourth year, and many were questioning if the South could ever be fully conquered militarily. Union General Ulysses S. Grant mounted a massive campaign in the spring of that year to finally defeat the Confederate army of General Robert E. Lee, but after sustaining significant losses at the Wilderness, Spotsylvania, and Cold Harbor, the Yankees bogged down around Petersburg, Virginia. As the fall approached, Grant seemed no closer to defeating Lee than his predecessors. Additionally, Union General William T. Sherman was planted outside of Atlanta, but he could not take that city. Some of the Radical Republicans were unhappy with Lincoln’s conciliatory plan for reconstruction of the South. And many Northerners had never been happy with Lincoln’s 1862 Emancipation Proclamation, which converted the war from one of reunion to a crusade to destroy slavery. Weariness with the war fueled calls for a compromise with the seceded states.

Explanation:

in the 1800s, chinese workers migrated to the united states, first to work in the gold mines, but also to take agricultural jobs, and factory work, especially in the garment industry. chinese immigrants were particularly instrumental in building railroads in the american west, and as chinese laborers grew successful in the united states, a number of them became entrepreneurs in their own right. as the numbers of chinese laborers increased, so did the strength of anti-chinese sentiment among other workers in the american economy. this finally resulted in legislation that aimed to limit future immigration of chinese workers to the united states, and threatened to sour diplomatic relations between the united states and china.