Complex sentence: At the start of "Operation Corporate" six Scouts from 3 CBAS were operating alongside three machines from No.656 Squadron AAC, and when 5 Infantry Brigade landed they were joined by another three Scouts from 656 Squadron.
Split into simpler sentences: At the start of "Operation Corporate", six Scouts from 3 CBAS were operating alongside three machines from No.656 Squadron AAC. When 5 Infantry Brigade landed, they were joined by another three Scouts from 656 Squadron.