World War I, when he was conscripted into the German army and had to fight on the Eastern Front, was a disaster for him as a pacifist and for the Esperanto movement in general.
His poetic works Verdkata testamento (The Will of the Green Cat) (1926) and Stranga butiko (The Strange Boutique)[1] (1931) are imaginative and humorous fantasies involving word games, characteristics also found in Prozo ridetanta (1928) (Smiling Prose).
From 1933 to 1935 he published the monthly satirical magazine La Pirato (The Pirate), which made him a sort of enfant terrible of the Esperanto movement, one for whom there were no secrets and for whom everything was an occasion for humour.
His masterwork, published after World War II, is Kiel akvo de l' rivero (Like the water of the river), considered as his most significant and most moving book.
This is a partly autobiographical novel of a young Frenchman from the Franco-German frontier who comes to Berlin after graduation but must flee at the outbreak of war in 1914.