[note 1] During the war years he served as a lieutenant in the Royal Engineers, in Mesopotamia (1917-1919) and India (May-June 1919).
He was made a fellow of Imperial College in 1949 and an Officer of the Order of the British Empire (OBE) in 1962.
[4] Ellingham is best known for his diagrams plotting the Gibbs energy change for the reaction against temperature.
By normalizing the thermodynamic functions to the reaction with one mole of oxygen, Ellingham was able to compare the temperature stability of many different oxides on the same diagram.
In particular, he could show graphically that carbon becomes a stronger reducing agent as the temperature increases.