Messageries Maritimes was a French merchant shipping company. It was originally created in 1851 as Messageries nationales, later called Messageries impériales, and from 1871, Compagnie des messageries maritimes, casually known as "MesMar" or by its initials "MM". Its rectangular house flag, with the letters MM on a white background and red corners, was famous in shipping circles, especially on the Europe-Asia trade lanes. In 1977 it merged with Compagnie générale transatlantique to form Compagnie générale maritime. In 1996 CGM was privatized and sold to Compagnie Maritime d'Affrètement (CMA) to form CMA CGM.

The Compagnie Générale Transatlantique, typically known overseas as the French Line, was a French shipping company. Established in 1855 by the brothers Émile and Issac Péreire under the name Compagnie Générale Maritime, the company was entrusted by the French government to transport mails to North America. In 1861, the name of the company was changed to Compagnie Générale Transatlantique. The company's first vessel, SS Washington, had its maiden voyage on 15 June 1864. After a period of trials and errors in the late 19th century, the company, under the direction of its presidents Jules Charles-Roux and John Dal Piaz, gained fame in the 1910s and 1930s with its prestigious ocean liners such as SS Paris, SS Île de France, and especially SS Normandie. Fragilized by the Second World War, the company regained its fame in 1962 with the famous SS France, which suffered major competition from air transport and was retired from service in 1974. In 1977, the company merged with the Compagnie des Messageries Maritimes to form the Compagnie Générale Maritime. Then, in 1996, the company Compagnie Générale Maritime merged to form the CMA CGM.