Complex sentence: The siege of Quebec ended on 5 May 1776--8 June 1776-After enduring the retreat from Quebec, the regiment took part in the ill-executed Battle of Trois-Rivières, Canada.
Split into simpler sentences: The siege of Quebec ended on 5 May 1776. On 8 June 1776, after enduring the retreat from Quebec, the regiment took part in the ill-executed Battle of Trois-Rivières, Canada.