Leonidas succeeds as Agiad king after Cleomenes I
Leonidas I’s documented role is: He became Agiad king after Cleomenes’ end. In the causal graph this event strengthens Democratic Resilience, a driver that strengthens Having a say in government — an improving welfare path.
Read the full account
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. 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. 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. Driver 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. Accession is not the pass. Mixed effects of Leonidas succeeds as Agiad king after Cleomenes I are separate paths.
Why it matters
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.
That reading is an impact-path choice, not a property stored on the Fact itself.
Who was responsible
Contribution type and responsibility level for each recorded actor — not sole-author shorthand.
Leonidas I
PersonDirect responsibility
responsibility level 0.32 · verified
He became Agiad king after Cleomenes’ end. Dual kingship already existed; later Herodotus is the public carrier; unique year is conventional.
What changed
Fact → Driver → Indicator. Relationship strength orders the paths; it is not the observed indicator movement.
- FactLeonidas succeeds as Agiad king after Cleomenes I
- strengthensDriverDemocratic Resilience
- strengthensIndicators (3)Having a say in government
impact weight 0.3 · Effect from 1 January 489 · verified
A dated succession put a named Agiad into the dual-kingship file, distinct from Thermopylae as a battle.
Strengthens · Relationship strength 0.21 (weight 0.3 × strength 0.7)
Observed
29.8% of population aged 16-65 years · 8.13 below the normal line (2023)
Worse than normalTwo readings: 30.2% of population aged 16-65 years (2021) and 29.8% of population aged 16-65 years (2023).
20212023 Above normal = better
Strengthens · Relationship strength 0.14 (weight 0.3 × strength 0.45)
Observed
0.53 score from 0 to 1 · 0.34 below the normal line (2024)
Worse than normal125 readings, 1900–2024: rose from 0.17 score from 0 to 1 to 0.53 score from 0 to 1.
Above normal = better
Strengthens · Relationship strength 0.14 (weight 0.3 × strength 0.45)
Observed
0.55 index score (0-1) · 0.26 below the normal line (2024)
Worse than normalAbove normal = better
Evidence
The sources behind this fact and its verification state.
- 1.Britannica — Cleomenes I, succession of LeonidasEncyclopaedia Britannica · High credibility · verified
- 2.Britannica — Leonidas IEncyclopaedia Britannica · High credibility · verified
What the sources establish
Britannica independently dates Leonidas’s accession as distinct from Thermopylae. Official: Britannica — Leonidas I, accession (https://www.britannica.com/biography/Leonidas-king-of-Sparta (opens in a new tab); Encyclopaedia Britannica). Independent: Britannica — Cleomenes I, succession of Leonidas (https://www.britannica.com/biography/Cleomenes-I (opens in a new tab); 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 (opens in a new tab); Encyclopaedia Britannica). Independent carrier: Britannica — Cleomenes I, succession of Leonidas (https://www.britannica.com/biography/Cleomenes-I (opens in a new tab); Encyclopaedia Britannica).
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.
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.
Causal path
How this event connects to drivers and indicators in the graph.
- ActorLeonidas I
- contributed toFactLeonidas succeeds as Agiad king after Cleomenes I
- strengthensDriverDemocratic Resilience
- strengthensIndicatorHaving a say in government
Cite this page
Factrail. (2026). Leonidas succeeds as Agiad king after Cleomenes I. Factrail. https://factrail.ai/facts/leo-accession-489
https://factrail.ai/facts/leo-accession-489
Accessed 16 October 2026.
By the Factrail desk · Method: how we source and score · Last reviewed
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