What reason best explains why mcclellan's campaign was unsuccessful, despite his numerical advantage?

he had very little support in washington.
the south never had to face the full brunt of the union forces.
he moved too quickly for reinforcements to arrive

B.Lee was promoted to take command of the Army of Northern Virginia

pan-africanism or pan-africanism is a political, philosophical, cultural and social movement that promotes african twinning, the defense of the rights of african people and the unity of africa under a single sovereign state, for all africans, both africa as of the african diasporas.