Biography.guide
Home › People › Writer › Theodore I
Portrait of Theodore I

Theodore I

1290 – 1338

Marquess of Montferrat

Don't just read it — keep itBiographies to ownE-book · Audio · Video From $7 →

About Theodore I

Lived 1290 – 1338 (aged 47–48). Theodore I was a Byzantine writer.

Theodore I Palaiologos or Palaeologus (Greek: Θεόδωρος Παλαιολόγος, full name: Theodoros Komnenos Doukas Angelos Palaiologos) ( – 24 April 1338) was Marquis of Montferrat from 1306 until his death.

Life Theodore was the second son of Emperor Andronikos II Palaiologos and Irene of Montferrat. As the son of a reigning emperor, Theodore was styled Porphyrogennetos ('born-in-the-purple'). Around 1305, Theodore's mother attempted to negotiate a marriage with a sister of the childless Guy II de la Roche so that Theodore would inherit the Duchy of Athens.

However, when his uncle John I died in 1305, the male line of the Aleramici marquises of Montferrat became extinct. The March of Montferrat was passed to Irene's children. Patriarch Athanasius I of Constantinople blocked the candidacy of the elder son John, so Theodore went to Italy instead.

Theodore sailed to Genoa in 1306. In 1307 he married Argentina Spinola, daughter of Genoese magnate Opicino Spinola, Capitano del Popolo (co-ruler) of the Republic of Genoa. Spinola used his wealth to back Theodore's claim to Montferrat.

Theodore was opposed by Manfred IV of Saluzzo. Manfred was a vassal of the House of Savoy, and several marquises of Montferrat had Savoyard wives. King Charles II of Naples also claimed parts of the march. He gradually overcame these foes and secured the whole march. In 1310 he received the imperial investiture from Emperor Henry VII.

Theodore died in Trino Vercellese in 1338. He was succeeded by his son John II Palaiologos.

Marriage and issue Theodore and Argentina had: Yolande (1318–1342), who married Aimone, Count of Savoy John ΙΙ (1321–1372)

Writings Theodore is known to have authored an original military manual, titled Les Enseignemens ou Ordenances pour un Siegneur qui a Guerres et Grans Gouvernemens a Faire, often referred to as Les enseignements. Originally composed in Greek in 1326-1327 while Theodore was in Constantinople, it exists now only in the medieval French translation of Jean de Vignay. The work is one of the most interesting medieval military manuals in that it is not dependent on Vegetius' De Re Militari or any other known classical text. It thus serves as an example of the military thinking of the late Byzantine and Medieval worlds.

Ancestors

Biography shop

Don’t just read it —
keep it.

Full-length biographies made to live with: read them, listen on the way to work, watch them tonight.

  • E-book
  • Audio
  • Video
Browse the shop — from $7

Instant download · yours to keep · every purchase keeps this site free

Important facts

Born
1290, Constantinople
Birth century
Occupation
Nationality
Positions held
Marquis of Montferrat
Also known as
Theodore I Palaiologos

People in Theodore I's life

Named in this biography and alive at the same time

Contemporaries

People whose lives overlapped Theodore I's

Frequently asked questions

Who was Theodore I?

Marquess of Montferrat (1306-1338)

When was Theodore I born?

Theodore I was born in 1290 in Constantinople.

When did Theodore I die?

Theodore I died on 24 April 1338 in Trino.

What was Theodore I's occupation?

Theodore I was a writer.

What nationality was Theodore I?

Theodore I was Byzantine.

Sources & further reading

· Wikipedia: Theodore I

· Wikidata: Q389345

· DBpedia: Theodore I of Montferrat

Cite this page

APA: Biography.guide. (2026). Theodore I. https://biography.guide/theodore-i-writer/

MLA: "Theodore I." Biography.guide, https://biography.guide/theodore-i-writer/.

Chicago: "Theodore I." Biography.guide. https://biography.guide/theodore-i-writer/.

Data last updated: 2026-09-20 · Spot an error? Report a correction.

Page generated 2026-09-27 05:20 UTC