Complex sentence: After spending six weeks in improving the defences, they left a garrison of 2,500 men in charge and departed, burning Dalkeith and laying waste to the country for six miles around Edinburgh while making a leisurely withdrawal to Berwick.
Split into simpler sentences: After spending six weeks in improving the defences, they left a garrison of 2,500 men in charge and departed. They burned Dalkeith and laid waste to the country for six miles around Edinburgh while making a leisurely withdrawal to Berwick.