in 1806 campbell sailed with the 45th regiment as part of major-general robert craufurd's unsuccessful campaign to south america as part of the british invasions of the river plate. in 1807 he was taken prisoner during the second battle of buenos ayres (argentina); he was released and (after 75 weeks away from home) evacuated back to ireland when the commanding officer lieutenant-general john whitelocke surrendered and agreed to withdraw from the river plate and montevideo (uruguay).