Labarum
The labarum was the military standard of Constantine the Great, made after the vision he reported before the Battle of the Milvian Bridge in 312: a gilded spear with a crossbar, a square jewelled banner hanging from it, and the Chi-Rho inside a gold wreath at the top.
Meaning
Eusebius of Caesarea, who says he saw it, describes a long spear overlaid with gold, crossed by a bar to form the figure of a cross. On top was a wreath of gold and precious stones holding the Chi-Rho, the letter P crossed by X, the first letters of Christ’s name. From the crossbar hung a square cloth thick with precious stones and interlaced with gold, and the staff above it carried a golden half-length portrait of the emperor and his children. Constantine had others like it carried at the head of all his armies. The Catholic Encyclopedia adds, from the same Life of Constantine, that fifty soldiers of the imperial guard were chosen to guard and defend it, and calls the word labarum of uncertain derivation, probably familiar in the Roman army from the reign of Hadrian.
Origin and history
Two Christian writers of the fourth century, Lactantius and Eusebius of Caesarea, tell the story differently. Lactantius, writing in On the Deaths of the Persecutors, says Constantine was told in a dream to have the heavenly sign put on his soldiers’ shields, and marked them with the X with a line drawn through it and turned round at the top, the sign of Christ; he does not mention a standard, and Britannica contrasts the two: in Lactantius the soldiers paint the Chi-Rho on their shields, in Eusebius they carry the labarum. Eusebius, in his Life of Constantine, tells of a cross of light seen in the sky about noon, above the sun, with the words “Conquer by this”, then a dream in which Christ told Constantine to make a likeness of the sign, and then the goldsmiths who made the labarum. Eusebius says the emperor himself told him the story long afterwards, on oath.
Britannica sets out why historians weigh the two differently. Eusebius wrote after Constantine had died; the vision is absent from Lactantius and from Eusebius’s own earlier Church History; and Eusebius dates neither the vision nor the dream to 27–28 October 312, so when they happened on the march to Rome is an open question.
Conquer by this
The words most often linked with the labarum are not on it in Eusebius. In his account “Conquer by this” is written in the sky, in the vision. The Catholic Encyclopedia (1910) puts them on the standard itself, a purple banner with the Greek inscription TOUTO NIKA, “conquer by this”, the Latin “In hoc signo vinces”; Eusebius’s description of the banner gives only gold and jewels. Smith’s Dictionary of Greek and Roman Antiquities (1875) says the emblem of Christ was woven in gold on purple cloth.
How the form changed
The labarum did not stay one design. The Catholic Encyclopedia points to coins of Constantine’s reign: on one the portraits of the emperor and his sons are on the banner, not the staff; on another the banner carries the monogram and is topped by an equal-armed cross. In form it was an adaptation of the Roman cavalry standard, the Vexillum, with the pagan emblems replaced by Christian ones. The 1911 Encyclopaedia Britannica adds that it was sometimes fixed to the staff by one side, like a modern flag, and reports a supposition that the small scarf once tied to a bishop’s crook came from it.
Often confused with
The Chi-Rho on its own is older than the labarum and is a monogram, not a standard; the Catholic Encyclopedia says it was a familiar Christian symbol before Constantine and took his name only because the standards made it popular. The labarum is the whole standard, with the monogram at its top.
Read next
- Next in Historical flagsDerafsh KavianiThe Derafsh Kaviani, “the standard of Kava” or “of the kings”, was the legendary royal banner of the Sasanian kings of Iran. In the Shahnameh it began as a blacksmith’s leather apron raised on a spear; the Arab army that defeated the Sasanians at Qadesiya, about 637, captured it.
- The monogram at the top of Constantine’s standard.Chi-RhoA monogram of the first two letters of Christ's name in Greek, used by Christians as a symbol of Christ.
See also
Vexillum, Jolly Roger, Blackbeard’s flag, Calico Jack’s flag, Bartholomew Roberts’s flag, Emanuel Wynne’s flag.
Sources
- Eusebius, Life of Constantine, Book I, chapters 28–31
- Lactantius, On the Deaths of the Persecutors, Chapter 44
- Labarum (Catholic Encyclopedia), Catholic Encyclopedia, vol. 8 (1910), Catholic Encyclopedia, via New Advent
- Battle of Milvian Bridge (Encyclopaedia Britannica), Encyclopaedia Britannica (Wayback Machine copy, 9 April 2026), Introduction; Conversion and battle
- Signa Militaria (Smith’s Dictionary of Greek and Roman Antiquities, 1875), James Yates, in William Smith, A Dictionary of Greek and Roman Antiquities, John Murray, London, 1875, pp. 1044–1046, LacusCurtius (Bill Thayer), p. 1045
- Flag (1911 Encyclopædia Britannica), Encyclopædia Britannica, 11th edition (1911), vol. 10, Encyclopædia Britannica, via Wikisource, Roman standards
The same shape elsewhere
Browse symbols formed from circles, lines or squares and rectangles.
Researched, edited and approved by Rory Hansen before publishing. Last reviewed October 14, 2026. How we research
Added .