Martignac, Jean Baptiste Sylvère Gay, vicomte de (zhäN bätēstˈ sēlvĕrˈ gā vēkôNtˈ də märtēnyäkˈ) [key], 1778–1832, French statesman. He was elected (1821) to the chamber of deputies and was named a member of the council of state in 1822. In 1828 he was made minister of the interior and virtual head of the new cabinet by King Charles X after the fall of the ministry of the comte de Villèle. Martignac's cabinet, composed of both liberals and reactionaries, was ineffective; his liberal reforms were killed by the ultraroyalists. The king had never liked Martignac's moderate concessions to the liberals and in 1829 dismissed him and appointed the reactionary prince de Polignac to succeed him.