In this sketch of territorial development up to 1787 may be seen the elements of a national policy and a national system: the territories were practically colonies and inchoate states, soon to be admitted into the Union; while the expansion of the national boundary during the war was a presage of future conquest and enlargement; and, considering the military and naval strength of Great Britain, the only direction in which annexation was likely was the southwest. Although the Federal Constitution of 1787 acknowledged the difference between states and territories only in general terms, and made no provision for the annexation of territory, the spirit and the reasonable implication of that instrument was that the Union might be and probably would be enlarged; some writers at the time felt sure that republican government was applicable to large areas.[9] Hence it was neither unnatural nor unsuitable that the new nation should at once show a spirit of expansion: in 1795 and 1796 its boundaries were finally acknowledged by its southern and northern neighbors. Various wild schemes of invading Spanish territory were broached, but not till 1803 was the question of the Mississippi fairly faced. Repeating the bold policy of Louis XIV., Napoleon attempted to combine the military and colonial forces of Spain with those of France, in order to make head against Great Britain. As a preliminary, in 1800 he practically compelled the cession of the former French province of Louisiana, and thereby revealed to the American people that it would be a menace to national prosperity to permit a powerful military nation to block the commercial outlet of the interior. Hence, when Napoleon changed his mind and offered the province to the United States in 1803, there was nothing for the envoys, the President, the Senate, the House, and the people to do but to accept it as a piece of manifest destiny. The boundaries of the Union were thus extended to the Gulf and to the distant Rocky Mountains.[10] With a refinement of assurance the United States also claimed, and in 1814 forcibly occupied West Florida. In the same period began a purposeful movement for extending the territory of the United States to the Pacific. Taking advantage of the discovery of the mouth of the Columbia River by an American ship in 1792, President Jefferson sent out a transcontinental expedition, under Lewis and Clark, which reached the Pacific in 1805, and thereby forged a second link in the American claims to Oregon. By this time the Spanish empire was in the throes of colonial revolution, and in 1819 the Spanish government ceded East Florida and withdrew any claims to Oregon, Texas being left to Spain.