In 1922, Percy came to national notice by confronting Ku Klux Klan organizers in Greenville and uniting local people against them.

He served with distinction in World War I and was best known for his memoir, Lanterns on the Levee: Recollections of a Planter's Son, but also published poetry.

Never married, William Percy took in and adopted his cousin's three sons when they were orphaned as boys (after their father's suicide and their mother's death in a car accident).

Its investigator, Mary Grace Quackenbos, concluded the conditions constituted peonage, but Percy's influence with the state government and Roosevelt caused the report to be buried, and no action taken against the planter.

[2] White Democrats had continued to work to suppress Black votes and reacted to prevent another biracial coalition with Republicans and Populists, as had occurred in the 1880s.

The tactics caused the defeat of Percy, who was attacked as a representative of the aristocracy of the state and for taking a progressive stance on race relations.

He advocated education for Black people and worked to improve race relations by appealing to the planters' sense of noblesse oblige.

The issue of disenfranchisement of Black people caused the Democratic primary to become the deciding competitive race for state and local offices in Mississippi.

After his defeat, Percy retired from politics to run his model plantation at Trail Lake and to practice law for railroads and banks.

British investors hired him to manage the largest cotton plantation in the country [citation needed]; he received 10% of the profits.

In 1922, Percy rose to national prominence for confronting the Ku Klux Klan when it attempted to organize members in Washington County during the years of its revival in the South and growth in the Midwest.

During the devastating Mississippi flood of 1927, which covered millions of acres of plantations and caused extensive damage, Delta residents began frantic efforts to protect their towns and lands.

The former senator appointed his son, William Alexander Percy, to direct the work of the thousands of Black laborers on the levees near Greenville.

[5] Charles Williams, an employee of Percy on one of the largest cotton plantations in the Delta, set up camps on the levee that protected Greenville.