In addition all the five Powers reached an agreement strictly limiting the use of the submarine, ensuring its compliance with the rules generally recognised to be applicable to all surface vessels.
The London Naval Conference set out to achieve limitation of every category of ship in the largest Navies, and, if possible, re ductions in them as well. Reduction did not necessarily mean a reduction in the size of existing fleets. If the Conference could produce reductions in the programmes for expanding those fleets which the various Powers had already in project—programmes which would have been put into effect in the next few years but for a new Treaty of limitation—the Conference would have achieved its second object. The Conference did succeed in doing this. It also succeeded in actually reducing the existing fleets of all the three Powers in the categories of battleships, destroyers and submarines. But even had the Conference failed in these respects and achieved limitation alone, it would have been a signal contri bution to confidence, disarmament and peace between nations. For one of the most fruitful causes of international distrust and war in the past has been competition in building up armaments.
Agreed limitation stops that competition. In naval armaments competition had recommenced seriously after the breakdown of the Geneva Conference, but so far, at any rate, as the United States, Great Britain and Japan are concerned, the London Naval Treaty has ended it. Thus the Treaty starts a new era between those naval Powers in which their relations are free from the dis trust bred from hostile shipbuilding. The nations can take ad vantage of this during the next few years to improve the security offered by political machinery for settling international disputes, in which case the naval powers would, it is hoped, be induced at their next Conference to make further reductions in their naval forces. Thus disarmament will come stage by stage. The chief practical achievement of the London Treaty is that it calls a halt at certain figures to the building of every kind of war vessel, and it is for future Conferences to bring those armament figures lower and lower until they reach negligible proportions.