Final answer:
The Readjuster Party gained power in Virginia in 1881 when poor whites and blacks united against the planter elite.
Step-by-step explanation:
The Readjuster Party came to power in Virginia in 1881, when various groups representing poor whites and blacks united against the aristocratic planter elite known as the Bourbons. The Readjusters were led by William Mahone and aimed to readjust the pre-Civil War debts in order to lessen the financial burden on the farmers and endorse public education. This movement marked a unique instance of cross-racial cooperation in the South during the 19th century.