Captains Martín de Rivas and Andrés de Pez y Malzárraga conducted the fifth and final maritime expedition of the Spanish search for René Robert Cavelier, Sieur de La Salle's colony in the Gulf of Mexico. The Rivas-Pez expedition was the only one of the search effort to make extensive river explorations. It came in response to the confused testimony of Jean Jarry, a Frenchman found living among the Coahuiltecans in southwestern Texas. The expedition left Veracruz on August 8, 1688, while Alonso De León was gearing up for a new land march from Coahuila to look for the French colony. Sailing the same two piraguas of the Rivas-Iriarte expedition, each with a canoe in tow, Rivas and Pez were to reexamine the Tamaulipas-Texas coast, with particular attention to the Río Bravo (Rio Grande). After a week's delay at Tampico because of weather, the voyagers entered the Río de las Palmas (Río Soto la Marina) on August 24. Remaining on the river until the thirtieth, they explored upstream "20 leagues" in the canoes, observing several Indian rancherías and numerous Indians. The piraguas, evidently taking a different branch of the river, were able to ascend only four leagues. Leaving the Río de las Palmas, the ships entered the Rio Grande on September 2, as Indians appeared on shore making hostile signs. The two canoes, each with nine armed men, explored up the river for "36 leagues," the first known instance of Europeans sailing on the river. On September 7, three leagues before the turning point, a latitude computation indicated a position near the sites of present-day Roma and Ciudad Miguel Alemán. The explorers anchored each night in the middle of the river for safety against the Indians. As they withdrew, natives swarmed both banks, shooting arrows at the intruders. The aiming of a musket put them to flight. From the Rio Grande, the expedition proceeded to Matagorda Bay, where the voyagers explored for two weeks without threading the passage into Lavaca Bay that could have led to the French colony. During that time they had two encounters with Indians, doubtless the Karankawas responsible for the final destruction of La Salle's Fort St. Louis. At the bay mouth they met a friendly group who gave them fish. The second encounter almost cost a man's life. The natives, having signaled friendship and lain down their weapons, suddenly retrieved their bows and began shooting arrows at the Spanish emissary. The man was saved "only by a miracle." Withdrawing on September 25, the expedition returned to Veracruz at midnight the on September 29, leaving the discovery of the French colony for Alonso De León the following year.