Complex sentence: In practice, however, decimation led into complete disintegration of the "esprit de corps" of the unit as soldiers, seeing their comrades being slaughtered, not by the enemy but their own, lost completely their resolve and trust to the commanders.
Split into simpler sentences: In practice, however, decimation destroyed the "esprit de corps" of the unit. Soldiers, seeing their comrades being slaughtered, not by the enemy but their own, lost their resolve and trust in the commanders.