Passage: Because the Romans had to fight against the Franks, who plundered Cologne and Trier in 435, and because of other events Theodoric saw the chance to conquer Narbo Martius (in 436) to obtain access to the Mediterranean Sea and the roads to the Pyrenees. But Litorius, with the aid of the Huns, prevented the capture of the city and drove the Visigoths back to their capital Tolosa. Theodoric's offer of peace was refused, but the king won the decisive battle at Tolosa, and Litorius soon died in Gothic imprisonment from the injuries which he had received in this battle. Avitus went – according to the orders of Aëtius – to Tolosa and offered a peace treaty which Theodoric accepted. Perhaps the Romans recognized at that time the sovereignty of the Visigoth state.

Question: Access to which sea was Theodoric trying to gain by attacking Narbo Martius?
Mediterranean