Battle of Atoleiros
1384 CE.
Shown on the map at 39.021°, -7.626°.
The Battle of Atoleiros (Portuguese pronunciation: [ɐtuˈlɐjɾuʃ]) took place on 6 April 1384, between a Portuguese force and a punitive expedition from Castile sent by John I. The battle took place near the population centre of Fronteira in Alentejo. It was the first major battle of the 1383–1385 Crisis. Nuno Álvares Pereira had been chosen to protect the frontier in this area, amid fear that a Castilian force could enter Portugal here. He left Lisbon with 1,000 infantry, adding to the strength of his forces on his way to Atoleiros. The Castilian army consisted of some 5,000 men, mostly cavalry, which was besieging the village of Fronteira. As Pereira approached, the Castilians sent an emissary to him, attempting to persuade him to retire. He refused, and the Castilians advanced to meet him, lifting the siege. The Portuguese formed a defensive square. In the short battle that followed, the Castilian cavalry was unable to break the Portuguese formation, suffering heavy losses. The Portuguese suffered none, and the Castilians withdrew. The battle of Atoleiros represents the first effective use of “square tactics” on the battleground.
Text from the Wikipedia article Battle of Atoleiros, licensed CC BY-SA 4.0.