At the outbreak of World War I, the Cap Trafalgar was interned in Buenos Aires. Being able to leave Argentina, the ship meet with the old gun boat Eber at the island of Trinidad, where it was equipped with the guns of the non-combat ready gunboat until 31.08.1914. After an unsuccessful two week raid in the South Atlantic, the ship returned to the island to resupply, but was surprised by the British auxiliary cruiser Carmania . Being much better armed than the German ship, the Cap Trafalgar was sunk in an one hour battle on 14.09.1914.