I cannot possibly agree with that assertion. If anything the 1920s were about forging the foundations of intellectualism, anti-patriotic fervour and pacifism.
Anti-patriotic fervour? No. Politically, the first half of the 20th century in Europe, including the 1920s, was all about ultra-nationalistic fervour. That tendency was only reversed by the massive carnage that Europe saw in WWII, which eventually led to relatively peaceful, non aggressive political stances all over Europe.
I hardly think so. The First world war saw the death of all that, even before the end. Indeed part of the reason why the start of WW2 saw France, Belgium _and Britain_ running from combat with soldiers all over the place was because many had grown up with no real sense of patriotism. IMO.
If anything, WWI replaced nationalism with extremist nationalism. Or would you call the pre-WWII governments of Spain, Germany, Poland, Italy, Turkey etc. for intellectual, anti-patriotic goverments?