A year later, a disastrous epidemic of cholera broke out in Washington, and the citizens petitioned for Magruder to be placed in charge of the Western Hospital.

In 1856, incumbent mayor John T. Towers — a member of the controversial "Know-Nothing" American Party — declined to seek re-election.

He did, however, deal with the crisis of the June 1857 Election Riots, in which the Know-Nothings recruited a street gang from Baltimore, the Plug-Uglies, to come to Washington on its local Election Day and intimidate the voters at the polls; the Plug-Uglies turned away anti-Know-Nothing voters with rocks, guns, and knives, until some citizens brought weapons of their own and the violence grew into mob rule.

[citation needed] He was buried at Oak Hill Cemetery in Washington, D.C.[3] In 1887, the William Beans Magruder School was opened on the 1700 block of M Street NW.

[4] It was closed after the 1979-1980 school year, rehabilitated and reopened as the Magruder building, part of the Seward Square office complex.