The new century opened with a dramatic event that signalled a turning point in Italian history. On the evening of 29 July 1900, the anarchist Gaetano Bresci shot dead Umberto I, nicknamed respectively ‘the good King’ and ‘the machine-gun King’ by the bourgeoisie and the anarchists. Bresci's act avenged the bloody repression of the ‘bread riot’ in Milan when more than eighty civilians were killed by troops under the command of General Bava-Beccaris in 1898. The king had rewarded Beccaris for the successful operation by decorating him and appointing him senator.

Bresci's act provoked violent reactions. The conservatives and liberals attacked all anti-monarchist groups – socialists and republicans included. The socialist and republican press also condemned the deed; socialist lawyer Filippo Turati refused the regicide legal advice. The assassination stirred Tolstoy to express his views on the ineffectiveness of regicide in the article ‘Thou Shalt Not Kill’.

The anarchist movement seemed deeply shaken by the event, incapable of reacting effectively or assuming a coherent, homogeneous position. Initially, some anarchists did not openly support the assassination, others dissociated themselves from the deed or, like L'Agitazione, strongly condemned it. Anarchist leaders outside Italy enunciated a more thoughtful and articulate analysis of the incident, providing a clear guideline for their comrades. Felice Vezzani in Geneva urged anarchists to break with the lynch-mob and to stop adopting bourgeois arguments. In September, Malatesta and other anarchists in London published a single issue significantly entitled Cause ed effetti. 1898–1900.

This publication was designed to defend anarchists from the widespread attacks from both conservative and socialist camps, most importantly by countering allegations that anarchism was inherently violent, and clarifying anarchists’ views on the use of force. Although the anarchist movement was comprised of several different tendencies, anarchists shared the belief that physical force was not a permanent feature of human relations and did not regard violence as a progressive factor in the social evolution of the human race.