Wiki is fascinating and amplifies Fuller's assertion:
In 1850, the Arana-Southern Treaty otherwise known as the Convention of Settlement was signed between Britain and Argentina. The Convention was referred to as a “peace treaty” many times by both sides; it represented a considerable triumph for General Juan Manuel de Rosas. Several authors, both Argentine and British, argue by failing to mention Argentina’s claim to the islands in the Convention, he effectively dropped it by acquiessance. The Convention of Settlement ended Argentina’s protests over the Falklands. After the Message to Congress in December 1849, the Falklands were not mentioned again in the Messages to Congress for 91 years until 1941.