William Allen; Former Head of Boeing Co.

William M. Allen, a retired Boeing Co. chairman who helped usher in the era of commercial jet air travel after World War II, died here Tuesday after a prolonged illness. He was 85.

Allen served as president of Boeing from 1945 to 1968 and then as chairman and chief executive officer until his retirement in 1972. It was during Allen’s tenure that Boeing developed the 707, 727, 737 and 747 series of jetliners and became the leading producer of commercial aircraft in the world.

Born in Lolo, Mont., Allen graduated from the University of Montana and Harvard Law School. He began his association with Boeing by handling its legal matters.

Allen joined the Boeing Co. as its president on Sept. 5, 1945, the day before the war ended. The company, which had geared up for war-related work, soon had no business and few employees.

Allen’s first major decision was to commit the Stratocruiser airliner to immediate production, which brought Boeing back into the commercial aircraft market.

One of his biggest gambles was a decision to risk $16 million of company funds to design and build a swept-wing commercial jet transport prototype. The Boeing 707 evolved from that plane.