Complex sentence: Joscelin was taken prisoner once again in 1122; when Baldwin came to rescue him, he too was captured, and Jerusalem was left without its King until Joscelin escaped in 1123, and obtained Baldwin's release the next year.
Split into simpler sentences: Joscelin was taken prisoner once again in 1122; when Baldwin came to rescue him, he too was captured, and Jerusalem was left without its king. However, Joscelin escaped in 1123, and obtained Baldwin's release the next year.