Explain why President Lincoln narrowed his war goals in 1861 to that o

Explain why President Lincoln narrowed his war goals in 1861 to that of saving the Union, and why in 1863, he expanded his goals to include freeing the slaves.

What will be an ideal response?

ANSWER
In 1861, Lincoln worried that Northern public opinion would not support a war for the abolition of slavery and that there were constitutional limitations to the president’s ability to end slavery. By 1863, he could justify emancipation as a military measure to weaken the Southern economy and its ability to wage war. Emancipation would also elevate Northern war goals to a higher plane, and would deter European recognition and aid to the Confederacy.