Complex sentence: With his death and the defeat of his brigade, for the Italians the battle was definitively lost at 12:30 a.m. Baratieri started a disorderly retreat, protected by the remnants of the 4th Infantry Regiment of General Ellena.
Split into simpler sentences: With his death and the defeat of his brigade, for the Italians the battle was definitively lost: at 12:30. After this, Baratieri started a disorderly retreat, protected by the remnants of the 4th Infantry Regiment of General Ellena.