Abraham Lincoln was the United State's sixteenth president. He opposed the expansion of slavery in the US. He was the president that issued the Emancipation Proclamation.
The Union's main two military leaders were Ulysses S. Grant and William Tecumseh Sherman. Grant was eventually then one to make Confederate general Robert E. Lee surrender to end the war.
The North's strategy was to surround the Confederacy and place them under a siege of some sort. Apart from that, the North also had a divide-and-conquer strategy which turned out in them being very offensive in the war.
One of the Union's advantages was their transportation. 72% of railroads in North America were in the North, allowing for quick transportation of troops and supplies.
Another one of the Union's advantages was their wealth. Since they still technically were the United States, they kept all of the government funds from the federal banks, allowing them to use that money to finance the war.
Last but not least, another one of the Union's advantages were their factories. The North could easily manufacture weapons, ammunition, and supplies from their many factories.