Complex sentence: He gained fame for his crucial role in the Mongol invasions of Japan and in 1274 during the first Mongol invasion (Bunye) he fought with his brother Aritaka and they were awarded.
Split into simpler sentences: He gained fame for his crucial role in the Mongol invasions of Japan. In 1274 during the first Mongol invasion (Bunye) he fought with his brother Aritaka and they were awarded.