Historians have concluded that this assignment provided valuable preparation for handling the challenging personalities of Winston Churchill, George S. Patton, George Marshall, and General Montgomery during World War II. Eisenhower later emphasized that too much had been made of the disagreements with MacArthur, and that a positive relationship endured. While in Manila, Mamie suffered a life-threatening stomach ailment but recovered fully. Eisenhower was promoted to the rank of permanent lieutenant colonel in 1936. He also learned to fly, making a solo flight over the Philippines in 1937 and obtained his private pilot's license in 1939 at Fort Lewis. Also around this time, he was offered a post by the Philippine Commonwealth Government, namely by then Philippine President Manuel L. Quezon on recommendations by MacArthur, to become the chief of police of a new capital being planned, now named Quezon City, but he declined the offer.