Complex sentence: Vice Admiral Durand-Viel became Chief of Staff in January 1931 and ordered a study replacing the 305 mm/55 guns with 330 mm/50 guns to outmatch the old Italian battleships.
Split into simpler sentences: Vice Admiral Durand-Viel became Chief of Staff in January 1931. He ordered a study replacing the 305 mm/55 guns with 330 mm/50 guns so as to outmatch the old Italian battleships.