Complex sentence: On 4 September 1942, he claimed his 150th victory, a Yakovlev Yak-1; he was the second pilot, after Gordon Gollob, to achieve this mark.
Split into simpler sentences: On 4 September 1942, he claimed his 150th victory, a Yakovlev Yak-1. He was the second pilot, after Gordon Gollob, to achieve this mark.