 In February 1808 , Agamemnon sailed with Rear @-@ Admiral Sir Sidney Smith 's flagship Foudroyant to Brazil , where they joined another squadron . At Rio de Janeiro it was discovered that Agamemnon was again quite worn out , with seams in her planking opening and some of her framing bolts broken . In October , Agamemnon and Monarch anchored in Maldonado Bay , in the mouth of the River Plate . They had been escorting the merchant vessel Maria , which had carried the surgeon Dr. James Paroissien to Montevideo where he was tasked with exposing a plot against King John VI of Portugal , who was in exile in Brazil . Whilst there , Monarch ran aground , requiring Agamemnon 's assistance to get her off . After learning that Paroissien had been imprisoned , the two ships put to sea , but were forced to return to Maldonado Bay when they encountered bad weather . After the ships returned to Rio in January 1809 , the ship was fully surveyed by the carpenter , who drew up an extensive list of her defects . 
