In a speech delivered by Newt Gingrich at the National Defense University, the former House Speaker shared the following:

Curtis Lemay told [Gingrich] the greatest contribution that he made to World War II, was that he had gone to the new Air Corps Command and Staff College in Montgomery, and had learned how to write a five paragraph field order [emphasis mine]. He got these huge complicated messages from 8th Air Force when he arrived as a Commander of a Wing in England, and he would rewrite them into the appropriate form, send it back and say, is this what you meant to send me? After about six weeks, 8th Air Force began issuing the new model.

The Field Order is now referred to as an Operation Order or OPORD.  The five paragraphs are as follows:

1. Situation: Depicts the overall enemy situation and the objectives of higher echelons
2. Mission: States the objectives assigned to the echelon issuing the order
3. Execution: Assigns subordinate objectives to each subordinate echelon that will lead to accomplishing the overall objective
4. Sustainment: Assigns necessary means for accomplishing the objective
5. Command and Signal: Provides non-routine communications instructions that subordinate echelons need for their mission

The full OPRORD format can be found here.

Sources:

• Transcript of Speech by Newt Gingrich to National Defense University on 14 December 2016 http://www.gingrichproductions.com/2017/01/trumpism-explained/
• Photo of General Curtis Lemay  https://upload.wikimedia.org/wikipedia/commons
• U.S. Army Ranger Handbook  https://www.benning.army.mil/infantry/rtb/4thRTB/content/PDF/Handbook.pdf