Campo Maior, Portugal  Campo Maior () is a municipality in the Portalegre District, Alentejo Region, Portugal. The population in 2011 was 8,456, in an area of . It is bordered by Spain on the North and East, by Elvas Municipality on the Southeast, and by Arronches Municipality on the West. Administratively, the municipality is divided into 3 civil parishes ("freguesias"):  Campo Maior was certainly a Roman settling - the ancient Muro Dam is close by - which was under control of the Moors for half a millennium. In 1219, it was conquered by Christian knights, the Pérez de Badajoz family, who then granted the village, which belonged to the municipality of Badajoz, to the Church of "Santa Maria do Castelo" (Saint Mary of the Castle). On May 31, 1255, King Alfonso X of Castile promoted the village to town status. In 1260, Bishop Friar Pedro Pérez, the Town Lord, granted the first charter ("foral") to the inhabitants of Campo Maior. He also introduced the town's first coat-of-arms, showing Our Lady and a lamb, with a legend ""Sigillum Capituli Pacensis"". On May 31, 1297, the Treaty of Alcanizes was signed by King Ferdinand IV of Castile and King Denis of Portugal, whereby Campo Maior, together with Olivença and Ouguela, was transferred to the Kingdom of Portugal. Under Portuguese sovereignty, Campo Maior went through an additional two Town Lords - Branca, sister of King Denis, in 1301, and Afonso Sanches, natural son of King Denis, in 1312 - before returning to King Denis's direct rule in 1318. The castle east of the village was rebuilt by King Denis in 1310. In the 17th and 18th Centuries, other fortifications were built and Campo Maior became an important garrison town. As a reflex of the influence of Castile in Campo Maior, the population and the garrison sided with Castile following the 1383–1385 Crisis. King John I of Portugal and Constable Nuno Álvares Pereira led their armies to Campo and besieged the town for six weeks, finally occupying it at the end of 1388. King John II (1481–1495) granted a new coat-of-arms to Campo Maior: a white shield, with the Arms of Portugal on one side, and John the Baptist, patron saint of the town, on the other side.