Col. Anthony Butler strutted like a peacock out of the White House on Aug. 7, 1829 with a seven-figure line of credit and secret orders to make the Mexicans an offer they could not refuse.

Andrew Jackson regarded the Rio Grande realm as “lost” territory, a legitimate part of the Louisiana Purchase that the Monroe Administration had seen fit to surrender to Spain. Five months into his presidency, he decided to buy Texas back and settled on five million dollars as a fair price.

While pon...