The reign of Leopold II (r. 1865–1909) first saw the rise of organised socialist political groups and parties, most notably among the industrial workers in the southern region of Wallonia.

[1] The International Workingmen's Association held its first conference outside Switzerland in Brussels in 1868 as Belgian socialism, under figures such as César De Paepe, expanded dramatically.

He writes: There exists but one country in the civilised world where every strike is eagerly and joyously turned into a pretext for the official massacre of the Working Class.

He considers that the Belgian Army provoked the rioting which was used to justify the repression of the strike and accuses conservative political and commercial interests in Belgium of complicity.

Ultimately, he attacks the government of Walthère Frère-Orban for "conspicuously playing the gendarme of capital against labour" and threatens that the result will be the weakening of proletarian support for Belgian independence, enabling the possible future annexation of Belgium by the Great Powers.