Complex sentence: Following the conclusion of the war, the "Monsieur" was paid off at Deptford in March 1783, and was sold (for £820) on 25 September of that year.
Split into simpler sentences: Following the conclusion of the war, the "Monsieur" was paid off at Deptford in March 1783. She was sold for £820 on 25 September of that year.