Complex sentence: On 7 January the town was heavily shelled by the Nationalist troops and the Thälmann Battalion subsequently suffered appalling losses (only 35 men survived)--also Hugh Thomas said that many wounded were killed by the Nationalist "regulares".
Split into simpler sentences: On 7 January the town was heavily shelled by the Nationalist troops and the Thälmann Battalion subsequently suffered appalling losses, with only 35 men surviving. Historian Hugh Thomas has also claimed that many of the wounded were killed by the Nationalist "regulares".