After indecisive fighting during the first year of its existence, the army seized the Spanish port of San Sebastián in August 1794.

By the time the Peace of Basel was signed on 22 July 1795, the Army of the Western Pyrenees held a significant portion of northeastern Spain.

The Army of the Pyrenees was formed on 1 October 1792 and a former Minister of War, Joseph Marie Servan de Gerbey was appointed to lead it.

Servan's new army covered a front from the Garonne River in the Pyrenees to the Bay of Biscay, then up the coast to the Gironde estuary.

In addition to 18 free companies, there were the following National Guard infantry battalions, Aldudes, 3rd Dordogne, 3rd Landes, 4th Lot-et-Garonne and Paris Louvre.

While the army's soldiers initially suffered due to lack of supplies, by the end of the war the troops were well equipped by their logistical base at Bayonne.

[5] Because Servan was associated with Jean-Marie Roland, vicomte de la Platière of the fallen Girondist faction, he was dismissed on 4 July 1793.

Servan was temporarily replaced by Anne François Augustin de La Bourdonnaye until 11 July when Pierre Joseph du Chambge d'Elbecq arrived to take command.

[6] On 8 September 1793 the Minister of War sent Thomas-Alexandre Dumas to take command of the army and promoted several officers to general of brigade.

[8] Worn out by disputes with the overbearing representatives Jean-Baptiste Cavaignac and Jacques Pinet, Muller resigned his post since his triumph kept him safe from the guillotine.

He enjoyed good luck in that the Reign of Terror ended on 27 July 1794, and with it the French government's practice of executing unsuccessful generals.

[12] Though Cavaignac, Pinet and Pierre-Arnaud Dartigoeyte were soon replaced, the new representatives such as Pierre-Anselm Garrau also tended to meddle in military decisions.

A siege train was assembled at Bayonne under Armand Samuel de Marescot in preparation for attacking the fortress of Pamplona.

The Spanish commander in the west, Ventura Caro mounted a quick offensive across the lower Bidasoa River near Hendaye.

Massing the army's grenadier companies into one body under Théophile Corret de la Tour d'Auvergne, Servan sent them to recapture Saint-Pée-sur-Nivelle.

[20] On 22 June Servan pushed the Spanish left wing back to the Bidasoa, capturing the Montaigne Louis XIV redoubt.

The same day, Jacques Lefranc seized the Izpegi Ridge and other French troops captured positions near the Maya Pass.

[25] On 23 June Ventura Caro's 8,500 Spanish soldiers were repulsed by a French force defending the fortified Mont Calvaire.

[26] On 10 July Antoine Digonet's 4,000-strong brigade drove the Spanish and French Royalists from their defenses atop Monte Argintzo (Arquinzu).

[27] On 23 July, the Army of the Western Pyrenees opened the Battle of the Baztan Valley by attacking the Spanish with the three front-line divisions of Moncey, Delaborde and Frégeville.

[29] Frégeville advanced toward Lekunberri while Delaborde marched over the Belate Pass, defeating Antonio Filanghieri's 2,000 troops.

On the 16th Delaborde and Jean Castelbert de Castelverd beat 4,000 Spaniards at Eugi and the next day drove them farther east.

After Cagigal was forced back on Orbaizeta, Pedro Téllez-Girón, 9th Duke of Osuna ordered a general retreat to avoid encirclement, leaving behind 1,500 prisoners and 40 field pieces.

On 12 July, Dessein started south with 4,500 troops, capturing 25 guns abandoned by Crespo and reaching Vitoria on the 14th.