Complex sentence: Tordenskjold describes in one of his later writings of the new artillery station being heavily fired upon by three Swedish galleys, a barge and three other vessels and the Danes were fired upon from Carlsten and its southern outworks.
Split into simpler sentences: Tordenskjold describes in one of his later writings of the new artillery station being heavily fired upon by three Swedish galleys, a barge and three other vessels. Additionally, the Danes were fired upon from Carlsten and its southern outworks.