The Treaty of Fomio, signed by Fao in 1793, marked the collapse of the first anti-French alliance. However, less than 5 years later, due to Napoleon's expedition to Egypt, Britain took the opportunity to encourage European countries to re-form a second anti-French alliance.
Napoleon's return to Paris was in the summer of 1799, and the nascent regime was waiting for him to take control. But he did not know that at this time of the following year, another war awaited him, and he would use the victory of this war to completely disintegrate the anti-French alliance, which was the Battle of Marengo.

First, the return of the general, the foggy moon Paris
In 1799, when France was in chaos and the Royalists in the west and south were in rebellion, the Governorate of Paris overthrew the Bourbons in Naples and forced the Sardinian king to abdicate, completely angering the six european countries, and the anti-French alliance was rebuilt in this context. In less than half a year, France suffered heavy losses in Italy, the Netherlands and other places, and the fruits of Napoleon's victory in the first expedition were lost. When Napoleon learned of this in Egypt, he resolutely decided to return to Paris to save the crumbling France.
Soon, Napoleon's "Moon of Mist" coup was supported by bankers and troops, and he forcibly dissolved the Senate and Parliament and established a provisional government, seizing the supreme ruling power himself. On the one hand, he promulgated a constitution to stabilize civil unrest, on the other hand, he quickly raised armaments to deal with foreign enemies, and tried to take diplomatic relations to show favor to Britain and Austria, and ease the pressure of the coalition forces on Paris.
However, the Anti-French League decided to restore the Bourbon Dynasty, and neither side could negotiate, and war once again inevitably came.
2. Reorganize the legion and attack the Austrian army again
Subsequently, Napoleon saw that the most suitable battlefield was undoubtedly Italy, but "pinch your fingers", Paris wanted to support this war at least sixty million francs, and France had already seen the bottom of the national treasury because of the consumption of the long war, he did not hesitate to borrow usurious loans from Portugal and the Netherlands, and collected this huge amount in a short time. When the funds were plentiful, a plan to crush the Austrian main force gradually took shape. However, the existing legions were still tied to the two flanks of the border, and Napoleon needed a new "reserve" legion.
Due to the extraordinary ability of the military ministers appointed by Napoleon, a legion of tens of thousands of people quickly assembled in Dijon. In order to conceal his sights, Napoleon also specially compiled a series of fake news to convince the Allied forces that this legion was illusory, and he began to declare in confusion that the legion would be pulled to the vicinity of Swabia, and the real legion would be secretly transferred to Geneva and Lausanne, and they would follow the example of Hannibal of Carthage, trying to climb over the snowy Alps and "flash" to the rear of the Genoa-Austrian army.
The French chose the Grand Saint Bernard Pass, which was characterized only by frequent avalanches. Napoleon settled in Paris and immediately rushed to Geneva, with his legion began to climb the mountain pass, the way also with the help of mountain people and monasteries, in less than ten days, the French army crossed the snowy mountains, the target was directly on the capital of Lombardy Milan, the Austrian commander Melas woke up at this time, and quickly gathered the scattered troops in the Alexandria area, and transferred the main force away from Genoa to meet the French army.
Third, light enemies in a battle, exchange victory and defeat
Melas was the first to encounter the French on the way to Milan, and was pinned down at the Battle of the Nava Bridge, Napoleon rearmed in Milan and pursued the Austrian army in the direction of the Orio River, Melas's main force was stranded on the north bank of the Po River, the French army did not encounter the Austrians for three consecutive days in the march towards Alexandria, Napoleon dispersed his forces for fear of deception, and as a result, a great war broke out when he reached the small village of Marengo on the Bormida River.
The two armies met, Melas was somewhat unable to withstand the fierce attack of the French, and after eight hours of fierce fighting had to retreat to Alexandria, Napoleon did not know the enemy situation, sent an aide-de-camp to find out the situation on the Bormida River, unfortunately the adjutant brought back the error message, so that Napoleon believed that Melas's main force was preparing to retreat in the direction of Genoa. As everyone knows, the entire strength of the Austrian army was stationed in Marengo, but Napoleon returned to the headquarters at this critical moment and failed to be on the front line in Marengo.
At dawn the next day, the Austrians poured out of the nest, three pontoon bridges appeared on the Bormida River, and the Austrians directly attacked the French positions, quickly forcing the French forwards to retreat to Marengo. Although the French right flank was supported, Marengo was completely lost in less than a morning, and Napoleon had just arrived at the front, and he ordered the only reserve to delay the Austrian attack on both flanks. However, under increasing pressure from the Austrian army, the French suffered heavy casualties, and Napoleon was forced to order a full retreat, seeing that the defeat was imminent.
At this moment, Melas was overconfident, mistakenly believing that Marengo's overall situation had been decided, and he also sent someone to Vienna to report the victory, and he was slightly injured in the line of fire. At this time, the French army was in disarray, and only Napoleon was calm and self-assured, he was waiting for the Baud division on the Western Front to come to his aid, and there was a glimmer of hope for victory.
At dusk, seeing that the French army was about to collapse, the situation changed dramatically, Napoleon's reinforcements arrived, the French army immediately launched a fierce counterattack, artillery and heavy cavalry arrived, the Austrian army almost retreated from defeat to rout, and the French army turned defeat into victory.
Fourth, the battle was greatly won, and the alliance was defeated again
Before the Battle of Marengo, the Austrian army was very light enemy, did not believe that Napoleon would attack northern Italy from the Alps, but Napoleon seized the node that determined the outcome of the battle, he did not go south to aid Genoa, but quickly waved milan to "encircle Wei and save Zhao", forcing the Austrian army to retreat north to fight with it. Even in the face of defeat, Napoleon was able to seize the fighter and encourage the French to resist until reinforcements arrived, and eventually the goddess of victory took care of France and won the Battle of Marengo.
This battle was the first important battle commanded by Napoleon after he came to power, and if defeated, the royalists in Paris planned to restore the Bourbon royal family, but Napoleon was desperate and the fate of France was once again saved. When the news of this victory was received, the city of Paris was roaring with salutes, Napoleon had eliminated the only enemy on the continent, the external threat of this nascent regime had been temporarily lifted, and France was anxious for a short period of peace to recuperate.
The Battle of Marengo made Vienna a great joy and sorrow, and Melas saw that the tide was gone and had to negotiate peace. However, the whole of Austria did not accept defeat, and it was not until after the defeat of the French army at the Battle of Hohenlinden in the winter of that year, when Napoleon led his troops to the city of Vienna, that Austria reluctantly signed the Treaty of Lunéville, and lost money to France on the basis of the earlier Treaty of Formio.
The defeat of the Austrian army also isolated Britain on the mainland, and in 1800 Russia withdrew from the European battlefield because of the division of the alliance, and now only Britain is left with the alliance. In 1802, Britain had to sign the Treaty of Amiens with France, a brief truce between the two countries, which also meant the collapse of the Second Coalition against France, and the nascent French regime was given a precious respite.
Reference materials:
1. "Napoleon's Biography"
2. "Napoleonic Empire"
3. The Biography of Napoleon I