Complex sentence: The king was ambitious and had succeeded in beating troops from Chu, Wei and Qi and annexing Teng at first, but the kingdom was finally annexed by Qi in 286 BC, while troops from Chu and Wei served in behalf of Qi.
Split into simpler sentences: The king was ambitious and had succeeded in beating troops from Chu, Wei and Qi and annexing Teng. However, the kingdom was finally annexed by Qi in 286 BC, with troops from Chu and Wei serving on behalf of Qi.