[7] After the bad harvest of 1846, after the economic crisis year of 1847 and after the French Revolution of 1848, political unrest also flared up in the Kingdom of Prussia with demands for democratic reforms and national unity.
The task of the Bürgerwehr was the "protection of legal freedom, preservation of concord and peace among all members of civil society, defence against any disturbance of public order".
In the initial phase of the revolution, Cantador belonged to the moderate forces that rejected the abolition of the monarchy through the proclamation of a Republic based on the French model, as the early socialist inspired Düsseldorf People's Club around Ferdinand Lassalle, Paul von Hatzfeldt and Julius Wulff was striving for.
On 19 March 1848, Cantador donated a black-red-gold flag, the symbol of German popular sovereignty and the national unity of Germany, which was subsequently hoisted on the Rathaus Düsseldorf [de].
At the Festival of the German Unity on 6 August 1848, which had been organised by men from the citizens' militia, the Association for Democratic Monarchy, Düsseldorf painters and members of the newly founded Düsseldorf gymnastics club after the election of Archduke John of Austria as Reichsverweser, Cantador appeared as keynote speaker alongside Lord Mayor Wilhelm Dietze.
The event took place in Düsseldorf on what was then Friedrichsplatz – in front of a Germania figure made of wood, cardboard and canvas, designed by Karl Ferdinand Sohn and created by Dietrich Meinardus, with raised sword in her right hand, 15 feet high, and in front of a black, red and gold standard with a double-headed, uncrowned imperial eagle as the emblem of the German Confederation adopted by the Frankfurt National Assembly in March 1848.
[13] When King Frederick William IV of Prussia visited his nephew Friedrich in Düsseldorf during the Cologne Cathedral Building Festival on 14 August 1848, and on his way from Bergischer Bahnhof to Schloss Jägerhof, he drove along what is now Königsallee (then Kastanienallee) in an open carriage, he was met by anti-Prussian protests and pelted with horse dung.
This incident caused unrest among soldiers in the Prussian garrison on the evening of the same day, who eventually attacked Düsseldorf citizens with drawn sabres.
Cantador's moderate stance changed in the course of 1848, after the Rhenish liberal Prussian March (disambiguation) government under Ludolf Camphausen and David Hansemann had failed, Prussia had signed the Armistice of Malmö, perceived as a betrayal, in the Schleswig-Holstein Question, and news had arrived in Düsseldorf of the shooting of the deutschkatholische Robert Blum and the forced transfer of the Prussian National Assembly to Brandenburg an der Havel.
On 28 November, Cantador was questioned by the state procurator von Ammon about the accusation that he had exceeded his powers to declare the Bürgerwehr permanent, because a municipal council resolution had been required for this.
The Prussian government, which regarded Cantador as a leading figure in the revolution and suspected him of having conspiratorial connections to Berlin, had him arrested on 9 December 1848, like Ferdinand Lassalle and Wilhelm Weyers, the leader of the tax-refusal campaign, before him.
The Düsseldorf deputy of the Prussian National Assembly, Anton Bloem, wrote to the prosecution senate of the Court of Appeal in Cologne on 28 February 1849, stating that Cantador had not called for an attack but for the defence of public order.
Friedrich Engels attributed this in an article in the Neue Rheinische Zeitung to the fact that Cantador, despite his political appearance, had a lot of friends among the "Düsseldorf bourgeoisie".
Until the morning of the following day, bloody barricade fights occurred between members of the vigilantes and Prussian military, resulting in 16 deaths,[18] among them the young painter Ludwig von Milewski.
On 30 April 1851, Cantador wrote a letter from Philadelphia to Ferdinand Lassalle, expressing his hope that the revolution in Germany would soon break out again and that he would then return with many like-minded people.