During the Wars latter stages he was admitted to the state bar and won election to the Virginia House of Delegates. From there he played a major part in that state's ratification of the United States Constitution. A request from President John Adams saw him travel to France in 1797 to help end attacks on American shipping in what was known as the XYZ Affair. Returning to the United States he won election to the United States House of Representatives and emerged as a leader of the Federalist Party in Congress. In 1800 he was appointed Secretary of State and became an important figure in the Adams administration. In 1801, Adams appointed Marshall to the Supreme Court and he quickly emerged as the key figure on the court and became its Chief Justice. Under his leadership the Court moved decisively to issuing a single majority opinion that clearly set out its ruling. Marshall upheld the principle of judicial review, whereby courts could strike down federal and state laws if they conflicted with the Constitution. With this the principle of separation of powers was more easily enabled and the position of the American judiciary as an independent and co-equal branch of government was made de-facto. John Marshall remains the longest-serving chief justice and fourth-longest serving justice in Supreme Court history. He died on July 6th, 1835.