Complex sentence: After Louis and Carloman had divided their father's realm at Amiens in March 880, the two brothers marched against Boso, took Macon and the northern parts of Boso's realm.
Split into simpler sentences: After Louis and Carloman had divided their father's realm at Amiens in March 880, the two brothers joined to march against Boso. They took Mâcon and the northern parts of Boso's realm.