Upon leaving the legislature he was appointed to an office in the
U.S. Treasury by
President Martin Van Buren and moved to Washington, DC. He served in the Treasury until 1850, at which time he started his own business prosecuting claims before the US government. He served on the inaugural committee for Presidents
James Buchanan and
Abraham Lincoln. In 1858, Berret was nominated as the mayoral candidate for the Anti-
Know-Nothing Party, a coalition of
political parties that formed in 1854 as an opposition to the Know-Nothings' electoral successes in the city. He was a staunch believer in the rights of naturalized citizens to vote. However, by 1858, the Know-Nothings were a spent force, and the U.S. political landscape was such that the
Republicans, who had once been a part of the Anti-Know-Nothing coalition, now stood independently from it as an opposition to President Buchanan and the
Supreme Court's decision in
Dred Scott v. Sandford. Thus Berret was pitted against
Richard Wallach, the
U.S. Marshal for the District; both men were of equal popularity, means, and political reputation, but on election day Berret won by 680 votes in an election that was marked by rioting, requiring the Marines to deploy, and the deaths of four citizens. With the outbreak of the
Civil War in 1861, the Republicans in the
U.S. Congress pushed through legislation that required all public officers in Union territory to take oaths of allegiance to the United States. When Berret refused, insisting that his oath as mayor of the nation's
capital should suffice,
Secretary of State William H. Seward had him arrested, jailed in the
Old Capitol Prison, then sent to
Fort Lafayette, New York. Three weeks later, when no evidence of collaboration with the enemy surfaced, Seward had Berret released and returned to Washington—on the condition that he immediately resign as mayor. Berret telegraphed his resignation to the Washington City Council, who had already elected Wallach to replace him. He was one of the most vocal opponents of the change of government in the District that occurred in 1871 and even led a lawsuit to stop it. He moved back to Maryland and was an Elector for Maryland in 1888, and as such was named President of the Electoral College that year. He was returned to the Maryland legislature representing Carroll County in 1891, serving on the Ways and Means committee. He later served on the inaugural committee for President
Grover Cleveland and as the first Vice-President of the Washington Monument Society. Berret died April 14, 1901, from the
flu and was buried in Congressional Cemetery in Washington, DC. His wife, Julia Wright, preceded him in death by 3 years. His last residence in Washington was at 1535 I Street N.W. The Berret School in Washington, DC was named in his honor. It was closed in the 1950s, but the building was eventually converted to condos in 2000 and it is now called the Berret School Lofts. ==References==