Complex sentence: Though both Napoleon and Jezzar requested assistance from the Shihab leader, Bashir, Bashir remained neutral, and when after several months of attacks Napoleon had to withdraw, his entire campaign to conquer Egypt and the East failed.
Split into simpler sentences: Though both Napoleon and Jezzar requested assistance from the Shihab leader, Bashir, Bashir remained neutral. After several months of attacks, Napoleon was forced to withdraw and his bid to conquer Egypt and the East failed.