Mayonnaise is believed to have been invented in 1756 during the French siege of Mahon, in Menorca, Spain. According to popular theory, the Duke of Richelieu's chef improvised the sauce using eggs and oil due to scarce supplies, naming it "mahonnaise" after Mahon. The sauce became known in France, later evolving into the mayonnaise we recognize today. Some sources also attribute its refinement to French chef Marie-Antoine Carême in the early 19th century, who improved the recipe by blending egg yolks with vegetable oil to create a lighter emulsion. While the exact origin is debated between France and Spain, the common consensus traces the invention to the French siege of Mahon in 1756 with subsequent popularization and refinement in France.