This was a US unrealised plan to send forces into the northern part of Brazil (25 May/mid-June 1940).
When the Germans smashed through the front of the Allies in western Europe within a week in May 1940, the government of the USA developed a concern that it might have to take major action to protect the vital and vulnerable Brazilian 'bulge' into the Atlantic Ocean. While the proposal of President Franklin D. Roosevelt for conversations with Brazil broadened into preparations for military staff conversations to be undertaken with the Central and South American republics generally, the US administration realised that any sort of conversations would take time and that it was essential for the USA to be prepared to take emergency action to deal with either an external attack or an internal Nazi-inspired revolutionary movement in South America.
On Roosevelt’s instruction, in the period 25/27 May 1940 the armed services created a wholly improbable plan, codenamed 'Pot of Gold', to despatch a 100,000-man force to Brazil. The Department of State agreed to send consular representatives to the Natal area to obtain a variety of current information needed to ensure that the movement of US troops to the bulge without impediment.
A German plot uncovered in Uruguay during the last week in May helped to confirm US fears and also alarmed the Brazilians sufficiently for the latter to send 5,000 rifles to the Uruguayan army.
By the middle of June 1940, the emergence of the 'Rainbow-4' plan had rendered 'Pot of Gold' superfluous.