Final answer:
The failure of the "40 acres and a mule" initiative was primarily due to President Johnson's revocation of Sherman's order, restoring land rights to former Confederates and disrupting land redistribution efforts for freed black individuals.
Step-by-step explanation:
The main reason for the failure of the "40 acres and a mule" initiative was President Johnson's decision to overturn Sherman's order. After the Civil War, General William Tecumseh Sherman issued Special Field Order No. 15, which temporarily settled approximately 40,000 freed black people on land confiscated from white planters and slaveholders. However, President Andrew Johnson revoked this order under the belief that the lands had never been legally seized and could not be confiscated during peacetime. Johnson's action restored the land rights of former Confederates, significantly undermining the prospects for an independent black yeomanry owning land where they once were enslaved.
Efforts by the Freedmen's Bureau to provide land to formerly enslaved individuals were also stymied by Johnson's policies. Despite some freed people managing to retain small plots, the size of these plots was often too small to support families, contributing to communities being in a state of near-perpetual poverty. Thus, President Johnson's policies greatly hindered the redistribution of land in the South, cementing the failure of the 40 acres and a mule initiative.