The Commander is an account-throughput Officer. It does not strengthen one fleet directly, but allows more active missions at the same time.
What does each level provide?
Commander scales by level: +1 fleet slot and +1 expedition slot per level. The relevant parallel fleet- and expedition-mission limits mechanic reads this bonus when the server calculates the corresponding action or account state.
What does this bonus combine with?
The Commander increases two separate limits at the same time. An expedition still consumes both a normal fleet slot and a separate expedition slot, so both capacities continue to matter. The final result can therefore depend on the Officer level together with technologies, buildings, active events and the current universe settings.
What does this Officer not change?
It does not speed up fleets, increase attack or directly increase expedition rewards. This distinction matters because similar-looking statistics in Inter-War do not necessarily use the same modifier.
How are new levels purchased?
Buying another level costs Dark Matter. The general formula is (current level + 1) × (2000 × Officer factor). The factor, requirements and maximum level come from the active universe catalog.
When is the bonus most noticeable?
It is most valuable for players who constantly use many slots and want to run more transports, attacks and expeditions in parallel. Do not assume one universal maximum level: worlds can use different configuration, so the Officers panel is the current source of truth for cost and level cap.
How does the Commander enter the slot formulas?
Commander is a separate component in both limits. Fleet slots use max(1, 1 + Computer Technology + Admiral bonus + Commander bonus), while expedition slots use max(1, Expedition Technology + Commander bonus + exploration-resort bonus). One Commander level can therefore improve both capacities at the same time.
Related FAQ: How does the Admiral, fleet speed and extra slot work? · How does the Technocrat and research/espionage bonus work?