Complex sentence: By the end of February 1945 JG 7 had claimed around 45 four-engined bombers and 15 fighters, but at this stage of war this success rate had no effect whatsoever on the Allied air offensive.
Split into simpler sentences: By the end of February 1945 JG 7 had claimed around 45 four-engined bombers and 15 fighters. But at this stage of war this success rate had no effect whatever on the Allied air offensive.