In response to <answer>Madero</answer>'s letter to action, Pascual Orozco (a wealthy mining baron) and Chihuahua Governor Abraham González formed a powerful military union in the north, taking military control of several northern Mexican cities with other revolutionary leaders, including Pancho Villa. Against <answer>Madero</answer>'s wishes, Orozco and Villa fought for and won Ciudad Juárez. After militias loyal to <answer>Madero</answer> defeated the Mexican federal army, on May 21, 1911, <answer>Madero</answer> signed the Treaty of Ciudad Juárez with Díaz. It required that Díaz abdicate his rule and be replaced by <answer>Madero</answer>. Insisting on a new election, <answer>Madero</answer> won overwhelmingly in late 1911, and he established a liberal democracy and received support from the United States and popular leaders such as Orozco and Villa. Orozco eventually became disappointed with the <answer>Madero</answer>'s government and led a rebellion against him. He organized his own army, called "Orozquistas"—also called the Colorados ("Red Flaggers")—after <answer>Madero</answer> refused to agree to social reforms calling for better working hours, pay and conditions. The rural working class, which had supported <answer>Madero</answer>, now took up arms against him in support of Orozco.
Orozco responded to whose letter to action?
Madero