Halsted and "Namur" were then assigned to Sir John Borlase Warren's squadron during the Atlantic campaign of 1806, until "Namur" was paid off in July 1807. In December 1807 he became Captain of the Fleet to the commander of the Lisbon station, Vice-Admiral Sir Charles Cotton, serving aboard Cotton's flagship . The British fleet were engaged in blockading a Russian fleet under Admiral Dmitry Senyavin in the Tagus after the outbreak of the Anglo-Russian War, but the Convention of Sintra allowed them to sail to Portsmouth. Cotton moved his flag to in December 1808, taking Halsted with him.