David, It is no surprise the Federal forces vacated Texas so quickly. There was an ongoing war with hostile Indians from the north and west; banditos from Mexico. The Texas Ordinance of Secession hotly blasted the U.S. Government for reneging on the promise to protect Texas citizens upon admission as a state to the Union. Below is a brief excerpt. Texans were fighting two wars, the War for Southern Independence and the Indian War. Feuding over resources was a huge conflict between the Texas and Confederate governments.

By the disloyalty of the Northern States and their citizens and the imbecility of the Federal Government, infamous combinations of incendiaries and outlaws have been permitted in those States and the common territory of Kansas to trample upon the federal laws, to war upon the lives and property of Southern citizens in that territory, and finally, by violence and mob law to usurp the possession of the same as exclusively the property of the Northern States.

The Federal Government, while but partially under the control of these our unnatural and sectional enemies, has for years almost entirely failed to protect the lives and property of the people of Texas against the Indian savages on our border, and more recently against the murderous forays of banditti from the neighboring territory of Mexico; and when our State government has expended large amounts for such purpose, the Federal Government has refused reimbursement therefor, thus rendering our condition more insecure and harassing than it was during the existence of the Republic of Texas.

These and other wrongs we have patiently borne in the vain hope that a returning sense of justice and humanity would induce a different course of administration.