Jefferson was never a 'libertarian', not ever. His second term as President was in practice a military dictatorship, enforcing an embargo to boot. He had little to do with the Jay Treaty, and he was opposed to universal suffrage, hardly a 'libertarian' policy, and owned around 600 slaves, of which he would have 10 year olds in his nail factory whipped for not producing enough nails or other 'infractions' like 'disobedience'.
His polices led directly to war; just because the war fell under the next President's watch doesn't absolve him. You seem to think those empires were letting him choose something.
Jefferson made some cruical first steps for democracy and his writing influenced Libertarian thinkers, he also:
A) Was the Author of the Declaration of Independence.
B) Passed the statute of Religious Freedom in Virginia.
All the Amercian Landowners were slave owners, its the dirty part of American History, Jefferson was no better and was a racist like the rest of them. He was not the only president or founding father to have owned slaves. In 1820 Jefferson worked with the governor of Virginia, Thomas Mann Randolph, Jr. (his son in law) on a plan to free all the newborn slaves in Virginia and send them to Haiti as free people. At this point Haiti was welcoming freed blacks emigrating from the US—over 13,000 American free blacks did emigrate there in the 1820s, so the location was attractive and there was a base for Jefferson's colony. Jefferson considered compulsory manumission and resettlement of newborn slaves to Haiti to be a practical solution to how to abolish slavery in Virginia. He wrote to U. S. minister to France Albert Gallatin: "My proposition would be that the holders should give up all born after a certain day, past, present, or to come, that these should be placed under the guardianship of the state, and sent at a proper age to S. Domingo [i.e. Haiti]. There they are willing to receive them, & the shortness of the passage brings the deportation within the possible means of [Virginia state] taxation aided by charitable contributions." The governor agreed with TJ and called on the legislature to endorse the plan but it refused.
Jefferson introduced the decimal system to the United States which was adopted and the dollar became the monetary unit instead of the British pound. He was anti-British and played a role in bringing around independence of the British colonies.
When Virginians reflect on the American Revolution, they often like to describe George Washington as its sword, Patrick Henry as its tongue and Thomas Jefferson as its pen. Jefferson expressed a sophisticated, radical vision of liberty with awesome grace and eloquence. He affirmed that all people are entitled to liberty, regardless what laws might say. If laws don’t protect liberty, he declared, then the laws are illegitimate, and people should rebel. While Jefferson didn’t originate this idea, he put it in a way that set afire the imagination of people around the world. Moreover, he articulated a doctrine for strictly limiting the power of government, the most dangerous threat to liberty everywhere.
The vital port city of New Orleans, “through which the produce of three eights of our territory must pass to market" was vital to the survival of the young US government. Napoleon said on the matter “The sale assures forever the power of the United States, and I have given England a rival who, sooner or later, will humble her pride.”