Complex sentence: Lyautey became disillusioned with French tactics in Europe and the disunity between the allies and engineered his own downfall and resignation in March 1917 and returned to Morocco by the end of May.
Split into simpler sentences: Lyautey became disillusioned with French tactics in Europe and the disunity between the allies. He engineered his own downfall and resignation in March 1917, returning to Morocco by the end of May.