Submarines were used by SOE to land agents and supplies in missions where air transport was out of the question.

In many of the early missions it was impractical to use air drops due to the jungle conditions, and the use of planes only became practical after the formation of Force 136.

Those that did succeed had a two fold success, the first in supplying the Malayan resistance forces with the arms and knowledge to harass the Japanese, and secondly as a moral booster to the local inhabitants that had new masters who were more violent in there occupation of Malaya.

The submarines themselves were Dutch as no British submarines were operating in the Far East at that time. Often the missions would fail due to unforeseen circumstances.

In order to land the parties would go ashore in a folboat, a canoe that could be folded up within the sub, then when the destination was reached taken topside and assembled.

In one such series of missions code named "Gustivus" submarines were the only method used throughout.

Gustavus 1. was the first mission in the far east to use submarines.  In this case they were to size a junk and its crew, and land on the coast of Malaya, the first since the British were kicked out by the Japanese after the surrender. It contained one British (Davis) and five Chinese with stores Radio arms and supplies of food for at least three months.

The aim was to find out just what level of resistance to the Japanese invasion was.

The use of the submarine was continued throughout the war in the east until the establishment of air drops as they had already tried in Europe.

Many operations conducted had the Captains of the submarines to be thankful for there skill and bravery.

The worse thing that could happen would be to have a mission take place with a full moon, this would have placed the captain and his submarine in danger of having his sub outlined on the sea and easy target for depth charges.