After departing Simonstown, she received the order to join the hunt for "Admiral Graf Spee". She left South Africa on 13 December in company with the cruiser and was in transit on 17 December when the Germans scuttled "Admiral Graf Spee" following the Battle of the River Plate. "Exeter" had been badly damaged in the battle with "Admiral Graf Spee", and "Dorsetshire" escorted her back to Britain in January 1940, before returning to South American waters to search for German supply ships. On 11 February, her reconnaissance aircraft spotted the German supply freighter "Wakama" off the coast of Brazil, which was promptly scuttled by her crew. "Dorsetshire" arrived on the scene shortly thereafter, picked up ten officers and thirty-five crewmen and sank "Wakama" to prevent her from being a navigational hazard. The following month, the President of Panama, Augusto Samuel Boyd, sent a formal complaint to the British government protesting against "Dorsetshire"s violation of the Pan-American Security Zone in the "Wakama" incident. In May, "Dorsetshire" underwent a short refit in Simonstown, before returning to Britain for a more thorough overhaul. On 23 June, she set out from Freetown to watch the French battleship , which left Dakar for Casablanca two days later. While "en route", "Dorsetshire" rendezvoused with the aircraft carrier "Hermes" off Dakar. "Richelieu" was ordered to return to Dakar by Admiral François Darlan later that day and she arrived on 27 June. "Dorsetshire" continued to monitor the French Navy off Dakar and on 3 July, the French submarines and attempted to intercept her. "Dorsetshire" was able to evade their attacks through high-speed manoeuvres. On 5 July, "Hermes" and the Australian cruiser joined her there. On 7 July, the squadron was ordered to issue an ultimatum to the French fleet, to either surrender and be interned under British control or to scuttle their ships; the French refused, so a fast sloop was sent in to drop depth charges under the stern of "Richelieu" to disable her screws. On 4 September, she was dry-docked at Durban and on the 20th she arrived back in Simonstown. She sailed for Sierra Leone the next day.