"But did any of the presidents ever think of marching troops upon the line?"

As I discussed in my last post concerning John Calhoun, Texas and Mexico, Senator Calhoun maintained that the treaty annexing Texas intentionally failed to define the border between that state and Mexico. He used this as the starting point for raising a “great question”: if the boundary was undetermined, what gave the president, rather than Congress, the right to determine where it lay?

But the great question comes up, has the Executive the right to determine what our boundary is? When we have a disputed boundary question – and we have had many – does it belong to the Executive or to Congress to determine it? There are two ways to do it. One is by negotiation and treaty, to be performed by the Executive and this body, in case the two nations agreed to negotiate. The other is, if the party disputes the boundary and will not come to terms, for Congress to declare where the boundary is, and maintain it, if need be, at the hazard of war.

By way of example, Calhoun cited the border between Maine and Canadian Great Britain. That border had been long undetermined, and yet no president had attempted to define the boundary himself by “marching troops upon the line”:

How long did the boundary of the Maine remain unsettled? From the acknowledgement of independence, in 1783, down to the time that the Senator from Massachusetts [Daniel Webster] closed it by a treaty [the Webster-Ashburton Treaty of 1842]. But did any of the presidents ever think of marching troops upon the line?

The late David P. Currie suggested that Calhoun did, in fact, raise an “intriguing” constitutional issue. While there was certainly something to be said for the proposition “that the president ought not to be required to surrender disputed territory to an occupying rival,” the fact was that Mexican forces had not advanced into “the controverted zone” – the area between the Nueces and the Rio Grande – before Zachary Taylor did so:

The intermediate possibility that the true boundary was unknown presented an intriguing opportunity for speculation. On the one hand there was a certain appeal to the defenders insistence that the president ought not to be required to surrender disputed territory to an occupying rival; he walked at least to be able to preserve the status quo. On the other hand, opponents pointed out with much just as that in the arguably analogous case of the Maine it was Congress that had empowered the president to prevent hostile military occupation of the disputed area. In any event, although Mexico had recently amassed troops along the Rio Grande, before Taylor’s advance it had made no military incursion into the controverted zone; Mexico had been in peaceable occupation of the Rio Grande valley, Texas in that of the Nueces for some years.