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Under the Tetrarchy a number of important military victories were secured.

Both the Dyarchic and the Tetrarchic system ensured that an emperor was nearby to every crisis area to personally direct and remain in control of campaigns simultaneously on more than just one front.

After suffering a defeat by the Persians in 296, Galerius crushed Narseh in 298 — reversing a series of Roman defeats throughout the century — capturing members of the imperial household and a substantial amount of booty and gaining a highly favourable peace treaty, which secured peace between the two powers for a generation.

Similarly, Constantius defeated the British usurper Allectus, Maximian pacified the Gauls, and Diocletian crushed the revolt of Domitianus in Egypt.