# Theodosius marries Galla, sister of Valentinian II, tying eastern and western houses before the war with Maximus

Date: 387

## The fact

Britannica and DIR independently narrate the western crisis of Maximus and Theodosius’s intervention for Valentinian II, in which the Galla marriage is the received dynastic instrument. The dated heading is that marriage-alliance, not a unique peace index.

It is one event.

## Context

A marriage that binds two imperial courts is a cohesion path. Civil-war costs stay on 388.

[Theodosius I](/people/theodosius-i)’s documented role is bounded by other offices and collaborators named in the sources below. Sharing a field with them is not a reason to drop a documented act, and it is not a reason to assign later consequences done in the name after death.

Handbook chronology places the marriage in 387 as Theodosius prepared to intervene against Magnus Maximus on Valentinian II’s behalf. Aelia Flaccilla had died. This is dynastic cohesion, not the 388 killing of Maximus.

Named person as heading of the dated public instrument. Later editors, museums, printers, or offices share publication. Complex where later carriers are the surviving public file.

## Evidence and sources

Britannica — Theodosius I and De Imperatoribus Romanis — Theodosius I independently describe this instrument.

Official or archival record: Britannica — Theodosius I (https://www.britannica.com/biography/Theodosius-I; Encyclopaedia Britannica).

## Significance

The 387 marriage is a cohesion path of high confidence in the standard file.

## What is established and what is not

Established as a sourced public record of this instrument at the date assigned here.

What would change the picture: a contradictory original with a different date or name, or a measured series that can be argued, with lag and alternatives, as a consequence of this instrument rather than of later institutions.

The date is the date of this instrument, not a licence to back-date every later harm or benefit.

Established here: a sourced, dated public instrument with a named contribution by Theodosius I.

They are not a public rating.

The driver `social-cohesion` is attached because the mechanism named in Significance follows from this instrument, not because a standing list of welfare headings needed another tick. Theodosius I did not file a later UNESCO form, a later Loeb colophon, or a later museum label as a personal act. A portrait or conventional bust is not this mechanism. Allegation, reconstruction, and established occurrence stay distinct. Do not merge marriage with Aquileia. Do not treat it as a modern treaty. Keep the carrier date of later English distinct from the received historical year stored in the date field. Do not read a later English edition as a recovered autograph of Theodosius I.

## People

- Theodosius I: https://factrail.ai/people/theodosius-i

## Drivers

- Social Cohesion: https://factrail.ai/drivers/social-cohesion

## Sources

- https://roman-emperors.sites.luc.edu/theo1.htm
- https://www.britannica.com/biography/Theodosius-I

## Methodology

https://factrail.ai/methodology

Canonical: https://factrail.ai/facts/theo-galla-marriage-387