 Once Lorenzo Maria Alier resigned as Carlist Catalan jefe in February 1936 one of the options considered was a triumvirate including Bau, but eventually it was Tomàs Caylà appointed the new regional leader.Though until the summer of 1936 Bau was active in the Cortes, he was heavily engaged in anti-Republican conspiracy, serving as a Carlist link to Renovación Española.Following the death of Calvo Sotelo he travelled to Portugal to negotiate details of the rebellion with José Sanjurjo, personally witnessing the crash of general's aircraft.