SIR EDWARD GREY PROPOSED THE LEAGUE OF NATIONS TO WOODROW WILSON IN JANUARY 1915

After finalising The Triple Entente, then feigning neutrality, then tricking Germany into invading Belgium, then tricking Great Britain into defending Belgium, and barely after the war got started, Sir Edward Grey then proposed a postwar organisation to uphold peace and security to US President Woodrow Wilson.

Not long thereafter, in January 1915, Grey began trying to persuade Woodrow Wilson of the need for a postwar collective security organization - that is, "some League for preservation of peace, to which the United States were a party and which could effectively discourage an aggressive policy or breach of treaties by anybody."

[source : The Political Economy of Grand Strategy, Kevin Narizny]

Wilson almost killed himself from exhaustion trying to persuade Americans to join The League of Nations. Grey was appointed British Ambassador to the USA to assist and advise Wilson on this. But Wilson failed.

The consequence was World War 2.

The result of WW2 was The United Nations...with its HQ in the USA.