Complex sentence: When the battle ended, the blood-soaked soil on the hill had been so thoroughly churned by shellfire and mixed with metal fragments that the soil contained between 500 and 1,250 splinters of metal per square meter.
Split into simpler sentences: When the battle ended, the blood-soaked soil on the hill was churned by shellfire and mixed with metal fragments. The soil contained between 500 and 1,250 splinters of metal per square meter.