John Grimaldi the First, lord of Monaco from 1427 to 1454, had to fight during all these years against the aims of his big neighbours – namely the Republic of Genoa, the duchies of Savoy and Milan –, eager to seize Monaco, strategic stronghold between Provence and Italy. Despite the determination he made to preserve the independence of his Rock of Monaco, John ended up selling, in the spring of 1451, his seigneury to Dauphin Louis, future king of France Louis XI, retaining only the government of the place in the name of the Dauphin. Thus, totally ignored, the delphinal banner waved for three years on the towers of the two castles of Monaco, until the death of John Grimaldi and the beginning of the reign of his son Catalan. Finally the place remained in the hands of the Grimaldi, the Dauphin having not executed the clauses of the bill of sale and having abandoned his plans of foreign Italian policy.
(full text in French)