In 1961, President John F. Kennedy appointed Laredo, Texas native, Thomas C. Mann, as the first U.S. Ambassador to Mexico from Texas. Long a proponent of settling a fractious border dispute involving a small piece of land known as “El Chamizal” on the El Paso-Juárez border, Ambassador Mann was given the authority by President Kennedy to negotiate a resolution. The eventual settlement was substantially similar to the binding arbitration award the United States had rejected in 1911. Mann’s quiet negotiations with citizens and leaders at all levels of government were ultimately successful, resulting in a large buyout and resettlement program, the rechanneling of the Rio Grande, and the construction of new international bridges and border control facilities. The peaceful resolution of the 100-year-old border dispute was ratified by treaty on January 14, 1964, and held by both nations as a diplomatic triumph. It is evident that Ambassador Mann seized an opportunity to bolster the tattered Good Neighbor relationship with Mexico, using his skillful diplomacy to achieve a result that satisfied both his desire to rectify arguable bad faith on the part of the U.S., and his goal to advance U.S. security by removing a target for anti-American communist groups in Mexico.
The Treaty of Guadalupe Hidalgo in 1848, established the international boundary between the United States and Mexico along the Rio Grande, following the deepest channel of the river. The Rio Grande proved to be a singularly unstable boundary line, changing course significantly along its entire length many times over relatively short periods of time. The problems this caused were manifold and resulted in a Boundary Convention in 1884, and the establishment of an International Boundary Commission in 1889. The river shifted course significantly to the south around 1864, leaving El Chamizal, a 630-acre parcel of land that had belonged to Mexico on the north (Texas) side of the Rio Grande. The U.S. and Mexico both claimed sovereignty over the slice of land.
By 1911, the United States and Mexico had agreed, under the terms of prior treaties, to submit the dispute to the International Boundary Commission for binding arbitration. At the conclusion of the arbitration, the Commission found, under the terms of the treaties, the majority of the 630 acres belonged to Mexico. The United States, citing a hypertechnical reading of the scope of the Commission’s authority, refused to accept the arbitral award. Thus, Chamizal, became a source of strong anti-American feeling among Mexicans. “If ever there was an American position which could be counted upon to cause suspicion and distrust, altogether this was it.” Every president since President William Howard Taft (1909-1913) had tried and failed to resolve the dispute. “Throughout it all, it seems clear that the Chamizal conflict was always close to the surface of Mexican popular consciousness and concern.” This was where the matter stood when Ambassador Mann took up his post in Mexico City in the spring of 1961.
President Kennedy’s appointment of Mann as the U.S. Ambassador to Mexico was widely celebrated in Mann’s home state of Texas as well as in Mexico. It had been said that “Mexico would not accept a Texan as the United States Ambassador.” However, Mann was born and raised in the Texas border town of Laredo. He often referred to his border upbringing and was fluent in Spanish, saying he had “learned Spanish before English.” He earned a law degree from Baylor University, practicing law for eight years before entering the foreign service during World War II. He rose quickly through the ranks thanks to his sharp, legal analyses, uncanny grasp of economic issues, and his command of Spanish. He had already served in the State Department under Presidents Roosevelt, Truman, and Eisenhower, with most of that experience focused on Latin America. Newspapers across Texas and Mexico ran the story, touting Mann’s reputation among Mexicans. Mann “is said to be friendly to Mexicans and is well liked by them.” Another newspaper reported, “on the whole, Mexicans are unabashedly happy about the appointment…” and “in Mann’s favor are a number of long and deep personal friendships among the men who steer Mexico’s foreign policy.” Mann’s public demeanor was that of a tough, blunt loner. “As one author put it, he was a man of few words who “not only didn’t have charisma, he didn’t believe in it.’” However, it appears that Mann’s diplomatic strength lay in his reputation for integrity and his warmth in small groups. Ladybird Johnson, wrote in her journal that Mann “possessed a deep love of Mexico” and that he seemed “made of tough fiber, but a loveable man.” He also was known for “having absolute loyalty to whoever was president.” One newspaper article described him as “quiet and efficient” and said “his mode of diplomacy is personal, usually conducted at small dinner parties or in chats in his paneled office.” These traits would serve him well in negotiating the Chamizal settlement.
Against the backdrop of the Cuban Revolution, Mann “regarded the containment of Mexico’s leftward drift as his central mission.” Having always desired to see the United States honor its treaty obligations concerning the Chamizal and seeing the chance to strengthen U.S.-Mexican relations, Mann proposed to President Kennedy the idea of revisiting the Chamizal issue. Kennedy gave Mann the go ahead to begin negotiations. Mann already had a close professional and personal relationship with Foreign Minister Manuel Tello, who was tasked by President López Mateos to negotiate for Mexico. The real challenge for Mann would be convincing El Paso and Texas that it was in America’s best interests to honor the spirit of the binding arbitration award. “Mann recognized the diplomatic importance of securing a Chamizal agreement and worked tirelessly, as one author has put it, to reach a settlement ‘palatable to his fellow Texans.’” In the years that had passed since the 1911 arbitration, American citizens had built homes and businesses in Chamizal. The small tract was now home to several schools, a meat packing plant, several small businesses, and some 4,000 residents. Negotiating the deal was complex, requiring the support of the City of El Paso, State of Texas, and Congress. According to Frank V. Ortiz, special assistant to Mann: he and Ambassador Mann started the process by meeting with local leaders in El Paso quietly and without publicity. El Paso leaders urged settlement, saying that without one the “future of El Paso and Juarez would be one of constant, bitter recrimination.” Mann and Ortiz next flew to Austin to meet with Governor Connally who pledged his support of the deal, but fearing a “backlash from “nationalist” Texans,” advised that the negotiations be kept confidential. Mann’s team then flew to Houston and won the support of civic leaders there. Ortiz recalls, “Ambassador Mann was so highly regarded and confidence in his judgment and his integrity was so high in Texas, that he almost alone won the support we had to have for a solution.”
The agreement was formalized in the Chamizal convention, signed by Ambassador Mann and Mexican Foreign Minister Tello in Mexico City on August 29, 1963. The disparity between Mexican and American reactions to the Chamizal settlement is telling. Media coverage in Mexico was immense, while it was mentioned only in passing in U.S. papers. As one author aptly put it, “[i]n a word, what was a mundane event in the United States was to the Mexicans one of the great moments in their recent history.” Although Mann and his team were able to build consensus to settle the dispute, not every Texan was happy with the result, and some wrote to Mann to express their displeasure. Mann's response to one such letter offers a glimpse of the principles that guided him: “I have no hesitation in saying to you that in my opinion when a Government or a man pledges his word it becomes a matter of honor to do what he undertook to do.” Indeed, in an echo of Mann’s sentiments, one newspaper commented that the State Department wanted the Chamizal Settlement “if for no other reason than to halt the teaching in Mexican schools that the U.S. does not honor international agreements.”
Why could Thomas Mann settle this issue that had long eluded others before him? According to one local official, “he understands the problems. He understands Mexico. He knows the importance, not just economically but emotionally and idealistically of the Chamizal.” Ambassador Mann answered this question himself, “I felt strongly that it should be done in the broader interests of both countries. We are neighbors, and this had been a thorn in our side exploited by nationalists and Communists and everybody else for fifty years. A constant source of friction in relations we thought ought to be removed.” His commitment to the Good Neighbor policy was authentic, but not without an agenda. “Although the United States yielded almost entirely to the historic Mexican contention, the Chamizal settlement was widely recognized as well worth the price.” Incredibly, "to Americans it was so singularly unimportant that to this day, except for people in the vicinity of El Paso and perhaps for international lawyers and a few others, it is largely unknown.” Yet, a national memorial now stands in El Paso on part of the land that was divided in the settlement to commemorate the event that best symbolizes Mexican-American friendship. Ambassador Mann retired from public service in 1966. A true citizen of the border, he was awarded the Aztec Eagle in 1968, the highest honor the Mexican government can bestow on a foreigner.