| Army of the Danube | |
|---|---|
 Fusilier of a French Revolutionary Army | |
| Active | 2 March – 11 December 1799 |
| Disbanded | 24 November 1799 and units merged into Army of the Rhine |
| Country |  First Republic |
| Engagements | Battle of Ostrach Battle of Stockach (1799) Battle of Winterthur (1799) First Battle of Zurich Second Battle of Zurich |
| Commanders | |
| Notable commanders | Jean-Baptiste Jourdan André Masséna Louis Marie Turreau |
The Army of the Danube (French: Armée du Danube) was a field army of the French Directory in the 1799 southwestern campaign in the Upper Danube valley. It was formed on 2 March 1799 by the simple expedient of renaming the Army of Observation, which had been observing Austrian movements on the border between French First Republic and the Holy Roman Empire. It was commanded by General Jean-Baptiste Jourdan, 1st Comte Jourdan (1762–1833).
The formation of the army was part of the French Directory's long term strategy to undermine Habsburg influence in the Holy Roman Empire, and, conversely, to strengthen French hegemony in central Europe after the wars of the First Coalition and the Treaty of Campo Formio in 1797. Despite the Treaty, Austria and France remained suspicious of each other's motives, and the purpose of the Army of the Observation was to watch for Austrian border transgressions. Understanding that the negotiations at the Congress of Rastatt were going no-where, the Army of Observation was instructed to cross the Rhine. Once across the Rhine, the Army of the Danube, was to secure strategic positions in southwestern Germany (present day Baden-Württemberg) and engage Archduke Charles' Habsburg army. In the meantime, the Army of Helvetia, under command of André Masséna, would secure such strategic locations as St. Gotthard Pass, the Swiss Plateau, and upper Rhine basin.
The army participated in four battles. In the battles of Ostrach and first Stockach, the Army of the Danube withdrew after suffering heavy losses. After reorganization, in which elements of the army were combined with Massena's Army of Switzerland, it withdrew after an engagement with Charles' superior force at Zürich in early June 1799; only in the Second Battle of Zurich did the Army of the Danube secure an uncontested victory. In December 1799, the Army of the Danube merged with the Army of the Rhine.