Complex sentence: It is common to encounter a claim that the Emancipation Proclamation did not immediately free a single slave, However, as a result of the Proclamation, many slaves were freed during the course of the war, beginning with the day it took effect.
Split into simpler sentences: It is common to encounter a claim that the Emancipation Proclamation did not immediately free a single slave. As a result of the Proclamation, many slaves were freed during the course of the war, beginning with the day it took effect.