Complex sentence: When the three Italian columns advanced on 15 January, there was little incentive left for Ras Desta's men to stand and fight; however, the Ethiopians did stand and attempted to hold their ground.
Split into simpler sentences: When the three Italian columns advanced on 15 January, there was little incentive left for Ras Desta's men to stand and fight. Even so, the Ethiopians did stand and they attempted to hold their ground.