Texans were likewise fearful of invasions or raids along the coastline, which could be discouraged by building fortifications and by stationing garrisons at such key points as Sabine Pass, Pass Cavallo (in Matagorda County). Port Aransas, and Galveston.[27] Continuous Union naval activity off Galveston caused that island to be regarded as a critical invasion objective. In fact, so serious was this threat that emergency plans were prepared for a quick evacuation of the city and possible destruction of the railroad bridge that linked the island with the mainland.[28] As Union craft tightened the blockade of Texas port towns, the main unblocked trade route from Texas to the outside world came to be the overland trail from San Antonio to Matamoros. This Mexican town contained a number of merchant houses that were willing to exchange valuable Texas cotton for goods needed by the South. To safeguard this supply route, to control border violence, and to intercept shirkers and Unionists attempting to cross the Rio Grande, Texas kept a number of state troops on patrol duty along the international river.[29] In spite of these manifold dangers and wartime conditions, Texas politics continued as usual. In November, 1861, an exciting contest allowed Francis R. Lubbock to replace Edward Clark as governor. Lubbock had wide political experience in the Lone Star State and, once assured of his narrow victory, he made a quick trip to Richmond to consult with principal Confederate leaders.[30] CAMPAIGNING: 1862 Throughout the early mobilization period Texans were anxiously observing the invasion of New Mexico by Lieutenant Colonel John R. Baylor and three hundred men of the Second Texas Rifles. As the summer of 1861 passed, the Baylor force pushed scattered Federal defenders northward along the upper Rio Grande.[31] Despite this early success, the Texas commander made it clear to leaders of the South that he would need many more soldiers to hold these gains. Southern control of the Arizona-New Mexico territory would increase the Confederate land area, it would give the new government access to rich minerals and poorly guarded Union supply dumps, it would secure western Texas from invasion, and it would give the South ownership of the Old Santa Fe Trail gateway to the Far West.[32]