The constitution confers upon congress the right of "calling forth militia to execute the laws of the Union, suppress insurrections, and repel invasions;" and another article declares that the president of the United States is the commander-in-chief of the militia. In the war of 1812, the president ordered the militia of the northern states to march to the frontiers; but Connecticut and Massachusetts, whose interests were impaired by the war, refused to obey the command. They argued that the constitution authorizes the federal government to call forth the militia in cases of insurrection or invasion, but that, in the present instance, there was neither invasion nor insurrection. They added, that the same constitution which conferred upon the Union the right of calling forth the militia, reserved to the states that of naming the officers; and that consequently (as they understood the clause) no officer of the Union had any right to command the militia, even during war, except the president in person: and in this case they were ordered to join an army commanded by another individual. These absurd and pernicious doctrines received the sanction not only of the governors and legislative bodies, but also of the courts of justice in both states; and the federal government was constrained to raise elsewhere the troops which it required.[159] The only safeguard which the American Union, with all the relative perfection of its laws, possesses against the dissolution which would be produced by a great war, lies in its probable exemption from that calamity. Placed in the centre of an immense continent, which offers a boundless field for human industry, the Union is almost as much insulated from the world as if its frontiers were girt by the ocean. Canada contains only a million of inhabitants, and its population is divided into two inimical nations. The rigor of the climate limits the extension of its territory, and shuts up its ports during the six months of winter. From Canada to the Gulf of Mexico a few savage tribes are to be met with, which retire, perishing in their retreat, before six thousand soldiers. To the south, the Union has a point of contact with the empire of Mexico; and it is thence that serious hostilities may one day be expected to arise. But for a long while to come, the uncivilized state of the Mexican community, the depravity of its morals, and its extreme poverty, will prevent that country from ranking high among nations. As for the powers of Europe, they are too distant to be formidable.[160] The great advantage of the United States does not, then, consist in a federal constitution which allows them to carry on great wars, but in a geographical position, which renders such enterprises improbable.