Complex sentence: Additional accounts from Zürich chronicles state that the city was saved by the gatekeeper's wife, one Anna Ziegler, who managed to lower the portcullis of the Rennweg gate just as the pursuing confederates were about to enter the city.
Split into simpler sentences: Additional accounts from Zürich chronicles state that the city was saved by the gatekeeper's wife, who was called Anna Ziegler. Ziegler lowered the portcullis of the Rennweg gate just as the pursuing confederates were about to enter the city.