Complex sentence: Others were decorated veterans and may have been motivated by a desire to see Russia, whilst some may have been unable to settle down after their wartime experiences, and could have viewed service as a means of postponing their return to civilian life.
Split into simpler sentences: Others were decorated veterans may have been motivated by a desire to see Russia. Some may also have been unable to settle down after their wartime experiences, and may have viewed service as a means of postponing their return to civilian life.