The strength of these forces was revealed when the February revolution of 1848 in Paris gave the signal for the outbreak of popular movements throughout Europe. The effect of the revolution in Vienna, involving the fall of Metternich (May 13) and followed by the nationalist movements in Hungary and Bohemia, was stupendous in Germany. Accustomed to look to Austria for guidance and material support, the princes everywhere found themselves helpless in face of the popular clamour. The only power which might have stemmed the tide was Prussia. But Frederick William's emotional and kindly temperament little fitted him to use "the mailed fist"; though the riot which broke out in Berlin on the 15th of March was suppressed by the troops with but little bloodshed, the king shrank with horror from the thought of fighting his "beloved Berliners," and when on the night of the 18th the fighting was renewed, he entered into negotiation with the insurgents, negotiations that resulted in the withdrawal of the troops from Berlin. The next day, Frederick William, with characteristic histrionic versatility, was heading a procession round the streets of Berlin, wrapped in the German tricolour, and extolling in a letter to the indignant tsar the consummation of "the glorious German revolution."