Source, in full
This is often attributed to U.S. Senator Hiram Johnson, but does not appear anywhere in his speeches. Arthur Ponsonby#Falsehood in Wartime (1928) quoted: "When war is declared, Truth is the first casualty", but the first recorded use seems to be by Philip Snowden in his introduction to Truth and the War, by E. D. Morel. London, July 1916: "'Truth,' it has been said, 'is the first casualty of war.'" Samuel Johnson#The Idler (1758–1760) expressed a similar idea: "Among the calamities of war may be justly numbered the diminution of the love of truth, by the falsehoods which interest dictates and credulity encourages."