US Senator, Presidential Cabinet Secretary. The nephew of US Senator and Vice Presidential candidate Theodore Frelinghuysen, he was adopted by his uncle at age three when his father died. After graduating from Rutgers University, New Brunswick, New Jersey in 1836, he was admitted to the New Jersey Bar Association, and began a law practice in Newark. He gained prominence for representing a number of banks and railroads, most notably the Central Railroad of New Jersey. He joined the Republican Party in the 1850s, and was a delegate from New Jersey to the 1860 Republican National Convention in Chicago, Illinois. He was appointed as New Jersey State Attorney General in 1861, and held that office though the Civil War. When United States Senator William Wright of New Jersey died in office in November 1866, Frederick T. Frelinghuysen was elected by the state's legislature to fill the vacancy in the Senate. He assumed his seat on November 12, 1866, and served until March 1869. His tenure in the Senate was marked by his opposition to many of President Andrew Johnson's post-Civil War Reconstruction policies, and voted to impeach President Johnson at his trial in 1868. Largely due to that opposition he was not re-elected for a full term in 1868. In 1870 President Ulysses S. Grant appointed him Minister to England, but he declined the appointment, instead opting to run for the United States Senate again when sitting New Jersey Senator Alexander G. Cattell declined to run again. He was successful in his re-election attempt, and in March 1871 Frederick T. Frelinghuysen once again rejoined the United States Senate as a Republican. His second term was marked by his participation on the judiciary committee, the finance committee, the committee on naval affairs, and others. Towards the end of his term he was again embroiled in Presidential politics when in 1876 he was named one of the fifteen members of the Electoral Commission to arbitrate the disputed Presidential election between Republican Rutherford B. Hayes and Democrat Samuel J. Tilden. Senator Frelinghuysen voted with the Republicans to awarded the election to Rutherford Hayes, with fellow Newark, New Jersey native Supreme Court Justice Joseph P. Bradley casting the deciding vote. Unsuccessful in his attempt to be reelected in 1877 due to a Democratic takeover of the New Jersey State Legislature, he returned to his law practice in Newark. After President Chester A. Arthur assumed the Presidency in 1881 following the assassination of President James A. Garfield, he re-organized his Cabinet, and appointed Senator Frelinghuysen as United States Secretary of State. Assuming that Cabinet position in December 1881, he served through the balance of President Arthur's Administration, leaving office in March 1885. Two months later, he died at his home in Newark.