Jan Ciermans

Portrait of Cosmander, Military Museum of the Fort Santa Luzia, Elvas

Jan Ciermans SJ (Latin: Ioannes Pascasius Cosmander; 7 April 1602 – 20 June 1648) was a Flemish Roman Catholic priest, mathematician, architect and military engineer. He was most active in Portugal. In 1646, he was expelled from the Society of Jesus for insubordination.

Biography

Jan Ciermans was born at 's-Hertogenbosch. He joined the Society of Jesus on November 6, 1619 and completed his novitiate in Mechelen. He studied philosophy, theology and mathematics at the Jesuit scholasticate in Leuven between 1619–1630, where he was ordained priest on April 4, 1634. He then taught mathematics in Antwerp and Leuven, and humanism in the former city. He was present in Portugal in 1641, when he transferred to the Jesuit college in Lisbon, which served as a transit point for missionaries bound for Asia.

Introduced to the court of King John IV, he impressed the latter with his knowledge of mathematics and the art of fortification. The king decided to keep him in Portugal.

As part of the war to Restoration War from 1640 onwards, against an impending Spanish invasion, it was necessary to undertake a complete restructuring of Portugal's border fortifications, adapting their fixed medieval structures to the artillery requirements of the time.

After the outbreak of hostilities with Spain, with the country's best fortification engineers serving overseas, Cosmander found himself as the best specialist in the kingdom. He accepted the position offered by the King, who appointed him to the rank of colonel of engineers in the Portuguese army. The Council of War appointed him to inspect the state of the fortifications in Lisbon and Setúbal.

Cosmander is probably the author of the plans for the two major fortifications built for the defense of Lisbon — the Fort of São João das Maias, from 1644, the Forte de São Pedro de Paço de Arcos — and near Setúbal, the Fortress of Saint James of Sesimbra and the works of Fort of Santiago do Outão.

In 1643, he found himself in Alentejo, alongside Philipe Guitau and Rui Correia Lucas, who had formed a council to ensure the province's defense. His military masterpiece was the fortress of Elvas.

He was then appointed superintendent of fortifications, which gave him authority over the other engineers, including the kingdom's chief engineer, Charles Lassard, who was considered less competent than he. Having become independent and no longer answering to the injunctions of the Superior General, Vincenzo Carafa, he was expelled from the Society of Jesus for insubordination in 1646.

On his way to supervise work on the Olivenza stronghold, he was surprised by the Spanish on the road between Estremoz and Elvas, in 1647. He then crossed over to the Spanish side, which was considered an act of treason against the Portuguese crown. In the attack against the Portuguese of Olivenza led by João Telo de Meneses, he was mortally wounded by a gunshot while trying to force a door.

Works

In Alentejo, he worked on the following fortifications:

• Évora (Fort Santo António da Piedade)
• Castle of Estremoz
• Gates and bastions of the second line of fortifications at Estremoz (17th century)
• Olivença fortress
• Campo Maior fortress
• Castle of Castelo de Vide
• Fortress of Juromenha, work on which was started but suspended due to high costs and technical difficulties. They were continued by Nicolas de Langres.

References

• Baldini, Ugo (2004), "The Teaching of Mathematics in the Jesuit Colleges of Portugal from 1640 to Pombal." In: Luis Saraiva & Henrique Leitão, eds., The Practice of Mathematics in Portugal. Acta universitatis conimbrigensis. Coimbra: Imprensa da Universidade, pp. 293–465.
• Nunes, António Lopes Pires (2005). Dicionário de Arquitetura Militar. Casal de Cambra: Caleidoscópio.

External links

• O Papel dos arquitetos e engenheiros militares na transmissão das formas urbanas portuguesas