Complex sentence: In the periods 1921-1926 and 1937-1940 he served in the French Foreign Legion in Morocco and wrote a book about his experiences there, and in 1926-1937 he served in the Foreign Ministry in France and in French Mandate of Lebanon.
Split into simpler sentences: In the periods 1921-1926 and 1937-1940 he served in the French Foreign Legion in Morocco and wrote a book about his experiences there. In 1926-1937 he served in the Foreign Ministry in France and in French Mandate of Lebanon.