When the powerful and populous France fell under the control of radical revolutionaries, the old regimes in the other countries of Europe had good reason to be scared. For that reason, they made several attempts to band together to face the French Revolutionary threat. The first of these had been the First Coalition of 1792-1797, which started collapsing as early as 1795. In that year, Britain recalled its army from the European continent. Also in 1795, Prussia, concerned with Russia's looming presence, made peace with France. Spain, ruled by a Bourbon King but extremely concerned with British sea power, allied with France (which had killed its Bourbon king). And in 1797, after Napoleon led the successful Italian campaign against Austria, the Treaty of Campo Formio was signed, creating the Cisalpine Republic and spelling the final end of the First Coalition.
During Napoleon's ill-fated Egyptian campaign, Admiral Nelson's British fleet demolished the French fleet at the Battle of Aboukir (The Battle of the Nile) in 1799. This rare triumph over France led to the formation of a Second Coalition against France, which lasted from 1799 to 1801. When, after getting demolished at the battle of Marengo, the Austrians signed the Treaty of Luneville in 1801, the Second Coalition fell apart. Soon after, the 1802 Peace of Amiens secured peace between the British and French. A period of Europe-wide peace ensued from 1802-1803, the only time during Napoleon's rule that no two European nations were at war. Of course, during this brief European peace, there still were conflicts going on in other parts of the world: notably, France was desperately trying to control the situation in Saint-Domingue (today Haiti), where Toussaint l'Ouverture was disobeying Napoleon's orders. In 1803, Napoleon sold the Louisiana Territory to the US for 80 million francs (15 million dollars).
Meanwhile, in Europe, Napoleon went ahead and made himself the official President of the new "Italian Republic", which had formerly been the Cisalpine Republic. Northern Italy had previously been a French-controlled puppet. Now, French dominance was stated outright. Napoleon also changed the name of the French-dominated "Helvetic Republic" to the "Confederation of Switzerland", himself ruling as the "mediator" of this "new" state. Furthermore, Napoleon carefully monitored events in the German principalities of Holy Roman Empire, as the rulers of these petty states competed for Napoleon's favor.
Even as the other European powers tried to unify against France, they were torn apart by suspicion of each other. In the period of the First Coalition, Austria and Prussia were so afraid of Russia at their Eastern flank that they kept most of their armies at home and did little to threaten France.
During the French Revolution, Toussaint l'Ouverture led the slaves on the French half of modern Haiti to rebel, and proclaimed himself for the revolutionary Republic, which made him lieutenant governor. In 1801, despite Napoleon's orders not to do so, l'Ouverture encouraged a revolt on the Spanish half of the island, freeing the Spanish slaves and creating a united Haiti. Although he had been involved in a slave revolt, Toussaint encouraged white landowners to return to running their plantations, but with wage instead of slave labor. He established a Haitian constitution and started making foreign policy by negotiating with the US. Napoleon would have none of this and sent General Charles Leclerc to take French power back in Haiti. Napoleon's forces fought a bloody struggle to depose Toussaint, who was very popular in Haiti, but they finally succeeded. In 1803, Toussaint died in a French jail. The mission Napoleon sent to Haiti to put down Toussaint l'Ouverture, though capturing Toussaint, ended up being expensive and difficult
In 1800, Spain had sold Louisiana to France, and Napoleon had envisioned Louisiana as a "breadbasket" for a vast French world empire. Toussaint's resistance in Haiti, however, turned him off to the idea of commitments in the New World, which would only be a drain on his European affairs. Furthermore, he increasingly realized that Britain's dominance at sea would allow them to harass his communication lines and trade routes with any New World colonies. The takeover of Haiti by the British in 1803 just reconfirmed his desire to get rid of New World holdings, and since US President Jefferson had expressed a interest in the Louisiana Territory, Napoleon decided simply to sell it rather than to get embroiled in a distant conflict, where his supply and communication ships would be vulnerable to the powerful British navy.