Percy Clinton Sydney Smythe, 6th Viscount Strangford was an Anglo-Irish diplomat.

The Portuguese royal court transferred from Lisbon to the Portuguese colony of Brazil in a strategic retreat of queen Maria I of Portugal, prince regent John, the Braganza royal family, its court, and senior officials, totaling nearly 10,000 people, on 27 November 1807. The embarkment took place on the 27th, but due to weather conditions, the ships were only able to depart on 29 November. The Braganza royal family departed for Brazil just days before Napoleonic forces invaded Portugal on 1 December 1807. The Portuguese crown remained in Brazil from 1808 until the Liberal Revolution of 1820 led to the return of John VI of Portugal on 26 April 1821.