On Jan. 17, 1936, The Army (usarmy) ordered 13 YB-17s, the plane they called the #FlyingFortress. Shown here are six YB-17 flying over #Manhattan. The Flying Fortress was described by General H. H. Hap Arnold as the backbone of the worldwide aerial offensive. The B-17 served in every #WWII combat zone. Boeing, Douglas and Lockheed Vega produced 12,731 B-17s at plants across the country, and the four-engine bombers became legendary for their ability to stay in the air after brutal combat. Learn more about the Flying Fortress in episode two of #TheAgeOfAerospace at theageofaerospace.com. Follow #Boeing100 and journey with us as we share 100 Boeing milestones in a countdown to Founders Day on July 15, 2016. #BoeingLovers and #avgeek: We want to see your Boeing, #instagramaviation and #aerospace memories. Join the celebration with #Boeing100 for a chance to be featured.