the bomber (or bombers) has never been precisely determined, it has been attributed by several historians to anarchists espousing direct action or propaganda of the deed. In addition to the language of the unsigned July warning leaflet, the Preparedness Day Parade had been organized by the Chamber of Commerce and the anti-union conservative business establishment to inspire patriotism and support for U.S. entry into the war, a development that could hardly fail to infuriate anarchists. Besides Mooney and Billings, several persons are thought to have been capable of carrying out such a violent attack, all of them anarchists and advocates of direct action. Others considered the bombing to be the act of an agent provocateur. Postwar research has led some historians to suspect involvement at some level in the bombing conspiracy by the anarchist Alexander Berkman, given his knowledge of the Lexington Avenue bombing conspiracy, his enthusiasm for revolutionary violence while editor of The Blast, and his hasty departure from San Francisco immediately following the Preparedness Day bombing. However, whether he was involved in the conspiracy or not, Berkman was almost certainly not the person who constructed the actual bomb, since he was known to have little or no technical skills with explosives. Another suspect group included the Galleanists, radical anarchist followers of Luigi Galleani, particularly the elusive Mario Buda. Buda, who was a bomb-maker of deadly repute, fit at least one witness's physical description of the bomber, and the Galleanists were known to utilize time bombs consisting of cast steel or iron pipes packed with dynamite and metal slugs or other types of shrapnel to increase maiming and overall casualties. While the Galleanists conducted most of their bomb attacks on the East Coast, there was a large and restive Italian anarchist community in San Francisco at the time, and many of them subscribed to Galleani's journal, Cronaca Sovversiva (Subversive Chronicle), which openly called for direct action via propaganda of the deed while glorifying the assassination of "militarists" and "capitalists". The Galleanists were known for their ruthlessness in choosing targets, had avidly participated in successful bomb attacks as far west as Milwaukee and Chicago, and in 1919 had unleashed a campaign of mail bombings to victims all over the country, including two booby-trap bombs sent to Fickert and his assistant Edward A. Cunha in San Francisco. Galleani himself wrote that police had not arrested "the right criminal", later telling investigators