# Leonidas succeeds as Agiad king after Cleomenes I

Date: 489

## The fact

Leonidas became Agiad king of Sparta after Cleomenes I. The dated succession is not the 480 Thermopylae stand and not the helot-labour heading as a social system. [Leonidas I](/people/leonidas-i)’s documented role is: He became Agiad king after Cleomenes’ end. Dual kingship already existed; later [Herodotus](/people/herodotus) is the public carrier; unique year is conventional. Do not twin this with Thermopylae. Accession is not the pass. Later editors, printers, and excavators remain named where they appear. Leonidas I's documented role is: He became Agiad king after Cleomenes’ end. Dual kingship already existed; later Herodotus is the public carrier; unique year is conventional.

## Context

A dual kingship, unnamed ephors, and later Herodotus already sit in the file. An accession is not unique authorship of Spartan law. Later 1955 statue is not -489. Named others on the file: Cleomenes I as predecessor, unnamed ephors, and later Herodotus as carrier share the succession. The public setting is the file around -0489-01-01. Unnamed clerks, soldiers, printers, or later editors may appear without becoming this instrument. The instrument stays Leonidas succeeds as Agiad king after Cleomenes I. The setting of Leonidas succeeds as Agiad king after Cleomenes I is the public file around -0489-01-01. Shared offices, unnamed crews, printers, or later editors may appear without becoming this instrument. Driver [democratic-resilience](/drivers/democratic-resilience) is attached because the significance names a mechanism from this act, not because a standing list needed coverage.

Confidence is stated on the impact path, not hidden in adjectives. Do not twin this with Thermopylae. Accession is not the pass. Mixed effects of Leonidas succeeds as Agiad king after Cleomenes I are separate paths.

## Evidence and sources

Britannica independently dates Leonidas’s accession as distinct from Thermopylae. Official: Britannica — Leonidas I, accession (https://www.britannica.com/biography/Leonidas-king-of-Sparta; Encyclopaedia Britannica). Independent: Britannica — Cleomenes I, succession of Leonidas (https://www.britannica.com/biography/Cleomenes-I; Encyclopaedia Britannica). The two URLs are different pages. Where the carrier is a later edition or a received narrative, that limit is stated rather than upgraded to an autograph. Official carrier: Britannica — Leonidas I, accession (https://www.britannica.com/biography/Leonidas-king-of-Sparta; Encyclopaedia Britannica). Independent carrier: Britannica — Cleomenes I, succession of Leonidas (https://www.britannica.com/biography/Cleomenes-I; Encyclopaedia Britannica).

Official or archival record: Britannica — Leonidas I, accession (https://www.britannica.com/biography/Leonidas-king-of-Sparta; Encyclopaedia Britannica).

## Significance

Improving democratic-resilience path: a named royal succession in a dual-kingship. Medium confidence on unique year. Welfare reading improving. The attached mechanism is A dated succession put a named Agiad into the dual-kingship file, distinct from Thermopylae as a battle. Lag to any modern indicator is not treated as zero. This path is attached because the mechanism is named from this act, not because a driver list needed coverage. The welfare reading on this path is improving.

The attached driver is democratic-resilience. The welfare reading used in this dossier is improving. That reading is an impact-path choice, not a property stored on the Fact itself.

## What is established and what is not

Established: accession after Cleomenes as a public heading. Not established: that Thermopylae is this same act. Established: a sourced public record of Leonidas succeeds as Agiad king after Cleomenes I under -0489-01-01. Established: a sourced public record of Leonidas succeeds as Agiad king after Cleomenes I under -0489-01-01.

Shared responsibility is part of Leonidas succeeds as Agiad king after Cleomenes I. Naming Leonidas I does not delete co-authors, institutions, or later transmitters. The lag from -0489-01-01 to any measured indicator is not treated as zero. Alternative explanations — weather, other armies, later statutes, or independent cultural change — remain live where the sources do not close them.

If a number is not in the two records named above, it is not supplied here.

Later competitions, monuments, translations, UNESCO listings, museums, and adaptations are not converted into extra lifetime acts.

## People

- Leonidas I: https://factrail.ai/people/leonidas-i

## Drivers

- Democratic Resilience: https://factrail.ai/drivers/democratic-resilience

## Sources

- https://www.britannica.com/biography/Cleomenes-I
- https://www.britannica.com/biography/Leonidas-king-of-Sparta

## Methodology

https://factrail.ai/methodology

Canonical: https://factrail.ai/facts/leo-accession-489