Complex sentence: Following a period of training with the NZEF in Egypt, Braithwaite served as a staff officer in Godley's headquarters, who was not only commander of the NZEF but also the New Zealand and Australian Division, during the Gallipoli Campaign which commenced in April 1915.
Split into simpler sentences: Following a period of training with the NZEF in Egypt, Braithwaite served as a staff officer in Godley's headquarters. Godley was not only commander of the NZEF but also the New Zealand and Australian Division during the Gallipoli Campaign which commenced in April 1915.