Complex sentence: Mary was out riding from Chartley with Bastian Pagez, her doctor Dominique Bourgoing and others, and they were surprised by armed soldiers who took them to Tixall in order to search Mary's rooms at Chartley and seize her papers.
Split into simpler sentences: Mary was out riding from Chartley with Bastian Pagez, her doctor Dominique Bourgoing and others, and they were surprised by armed soldiers who took them to Tixall. Their purpose was to search Mary's rooms at Chartley and seize her papers.