Operation Frankton, of December 1942. The mission was for Royal Marines to place limpet mines on German ships in the occupied Bordeaux Harbour, 62 miles along the Gironde River. Five cockleshell canoes set off from submarine HMS Tuna at the mouth of the river. Only two reached the harbour and carried out the raid, escaping with the aid of the French Resistance. The damage to the ships and the resulting disruption to German supply lines had a significant impact on the war effort.