 Complete the following phrase:  With the annexation of Texas within the United States and the MexicanAmerican War in 1846, several companies of Rangers were mustered into federal service and proved themselves at the battles of Palo Alto and Resaca de la Palma. From that moment on, their effectiveness as guerrilla fighters and guides to the federal army through a territory that they were familiar with marked the pace of the American offensive. Rangers played an important role in the battles of Monterrey and Buena Vista. The army, commanded by General Winfield Scott, landed at Veracruz in March 1847, and the Rangers once again provided valuable support at the ensuing Siege of Veracruz and the battles of Cerro Gordo and 