Next, I guess I have to explain the difference between the National Guard (a State Militia) and the U.S. Army (Federal) to you, you seem not to be real clear on the difference between the two, since you've listed National Guard interventions as part of your examples of the US Army enforcing civil law.
In order to understand the role of the U.S. Military in our country, you must first understand the natural aversion of the Americans at the time of the Revolution, to the age-old practice by European monarchs of using the military to keep the masses in place. The Founders themselves envisioned a militia-based military that would have no role in the enforcement of Civil Laws.
The Spanish-American War did not see any militarization of the borders, and the Pancho Villa raids sparked Pershing's Punitive Expedition into Mexico, not a militarization of the borders.
To the best of my knowledge, the US Army was too busy during either World War to take an active role in protecting the domestic borders, and that task was once again left to the Reserves, and the National Guard.
Unless of course, you can substantiate your claims that it did. Or substantiate anything at all that you posted for that matter.