In The Economic Consequences of Mr. Churchill, a pamphlet he wrote in 1925, Keynes argued that restoring the pre-war parity would generate deflation, with adverse effects on income, a contraction in  2  BIS Review 13/2003  the volume of business and economic crisis. The only way to avoid these effects was to reduce wages and prices. His warning went unheeded.
In the opinion of many scholars, the return of all the major countries to the gold standard with a marked revaluation of their currencies was the underlying cause of the Great Depression of the 1930s.