In 1806, the regiment took part in the disastrous expeditions to Spanish-controlled South America, then an ally of France during the Napoleonic Wars. Sir Home Riggs Popham had orchestrated an expedition against South America without the British government's sanction. This invasion failed, but a second invasion was launched. The regiment was part of this second force, under Sir Samuel Auchmuty. The British force besieged and captured Montevideo. In 1807, the regiment was part of the force, now under John Whitelocke, that tried to capture Buenos Aires, but this failed abysmally. The British force (including the regiment), was forced to surrender, and did not return home until January 1808.