Complex sentence: This unit flew its first mission on 6 September 1944 while the first group to fully convert to the A- 26B was 416th Squadron which entered combat on 17 November, while the 409th became operational on the A- 26 in late November.
Split into simpler sentences: This unit flew its first mission on 6 September 1944. The first group to fully convert to the A- 26B was 416th Squadron which entered combat on 17 November, and the 409th became operational on the A- 26 in late November.