# Constantine IV

> Byzantine emperor from 668 to 685

**Wikidata**: [Q41605](https://www.wikidata.org/wiki/Q41605)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Constantine_IV)  
**Source**: https://4ort.xyz/entity/constantine-iv

## Summary
Constantine IV was a Byzantine emperor who ruled from 668 to 685. As a key political and military leader of the Byzantine Empire during Late Antiquity and the Middle Ages, he is best known for his defense of Constantinople against the First Arab Siege (674–678), securing the empire's survival. His reign marked a critical period in Byzantine history, reinforcing imperial authority and religious unity.

## Biography
- **Born**: January 1, 652
- **Nationality**: Byzantine Empire
- **Occupation**: Emperor of the Byzantine Empire
- **Known for**: Defending Constantinople during the First Arab Siege (674–678) and stabilizing the Byzantine Empire
- **Field(s)**: Politics, Military Leadership

## Contributions
Constantine IV's most significant contribution was his successful defense of Constantinople during the **First Arab Siege (674–678)**, which prevented the Umayyad Caliphate from capturing the Byzantine capital. His military leadership ensured the survival of the Byzantine Empire during a critical period. Additionally, he played a key role in resolving the **Monothelite controversy** at the **Third Council of Constantinople (680–681)**, which reinforced orthodox Christian doctrine and imperial religious authority.

## FAQs
**1. When did Constantine IV rule?**
Constantine IV ruled the Byzantine Empire from **668 to 685**, succeeding his father, Constans II.

**2. What was Constantine IV’s greatest military achievement?**
His most notable military success was the defense of Constantinople during the **First Arab Siege (674–678)**, where he repelled the Umayyad forces using **Greek fire**, a devastating naval weapon.

**3. How did Constantine IV influence Byzantine religion?**
He convened the **Third Council of Constantinople (680–681)**, which condemned Monothelitism and reaffirmed orthodox Christian teachings, strengthening the empire’s religious unity.

**4. What was Constantine IV’s relationship with his family?**
He was the son of **Constans II** and father of **Justinian II**, who later succeeded him. His reign was marked by political stability despite internal and external threats.

## Why They Matter
Constantine IV’s leadership was pivotal in preserving the Byzantine Empire during a time of intense external pressure. His victory over the Arab siege not only saved Constantinople but also ensured the empire’s continued dominance in the Mediterranean. His religious policies, particularly the resolution of the Monothelite controversy, solidified the empire’s theological foundations, influencing Byzantine Christianity for centuries. Without his military and political acumen, the Byzantine Empire might have collapsed under Arab expansion.

## Notable For
- Successfully defending Constantinople during the **First Arab Siege (674–678)**
- Using **Greek fire** as a decisive weapon in naval warfare
- Convening the **Third Council of Constantinople (680–681)** to resolve the Monothelite controversy
- Being the father of **Justinian II**, a future Byzantine emperor
- Reinforcing imperial authority and religious orthodoxy

## Body
### Early Life and Ascension
Constantine IV was born on **January 1, 652**, as the eldest son of **Emperor Constans II**. He ascended to the throne in **668** after his father’s assassination, inheriting a empire facing external threats from the Arabs and internal religious divisions.

### Military Leadership and the Arab Siege
His reign was defined by the **First Arab Siege of Constantinople (674–678)**, one of the most critical conflicts in Byzantine history. Constantine IV employed **Greek fire**, a highly effective incendiary weapon, to devastate the Arab fleet, forcing their retreat. This victory secured Constantinople’s survival and halted Arab expansion into Europe.

### Religious and Political Reforms
In **680–681**, Constantine IV convened the **Third Council of Constantinople**, which condemned **Monothelitism**—a doctrine that had caused significant religious strife. This council reaffirmed the orthodox Christian position, strengthening the empire’s religious cohesion.

### Legacy and Succession
Constantine IV died on **July 10, 685**, and was succeeded by his son, **Justinian II**. His reign is remembered for its military triumphs and religious stability, ensuring the Byzantine Empire’s continuity during a turbulent era. His leadership set a precedent for future emperors in balancing military defense with theological unity.

## References

1. Virtual International Authority File
2. [Source](https://opac.sbn.it/nome/RMLV033337)
3. Freebase Data Dumps. 2013
4. CERL Thesaurus
5. Library of Congress Control Number
6. [LIBRIS. 2007](https://libris.kb.se/katalogisering/tr58c6xc3h1dxqk)
7. HMML Authority File