The Spur group joined and collaborated with the Situationist International, a restricted group of international revolutionaries, between 1959 and 1961. After a series of core divergences during 1960–1, the Spur members were officially excluded from the SI on February 10, 1962. The events that led to the exclusion were: during the Fourth SI Conference in London (December 1960), in a discussion about the political nature of the SI, Spur group disagreed with the core situationist stance of counting on a revolutionary proletariat; the accusation that their activities were based on a "systematic misunderstanding of situationist theses"; the fact that at least one Spur member, Lothar Fischer, and possibly the rest of the group, were not actually understanding and/or agreeing with the situationist ideas, but were just using the SI to get success in the art market; and the betrayal of a common agreement on the Spur and SI publications. The exclusion was the recognition that the Spur group's "principles, methods and goals" were significantly in contrast with those of the SI. This split however was not a declaration of hostilities, as in other cases of SI exclusions. A few months after the exclusion, in the context of Judicial prosecution against the group by the German state, Debord expressed his esteem to the Spur group, calling it the only significant artistic group in Germany since WW2, and at the level of the avant-gardes in other countries.