Where most Custodians keep their vigil within the Imperial Palace itself, the warriors of the Solar Watch look outward, standing sentinel over the wider Sol System and the hallowed worlds that surround the Throneworld. Theirs is the duty of the castellan, to watch the void-approaches and the near stars for any sign of the foe, and to fall upon that foe before it can ever come within reach of Terra. To them the defence of the Blessed Worlds is a sacred trust older than the Imperium's decline, and they discharge it with the tireless perfection of the Emperor's chosen.
The defining virtue of the Solar Watch is readiness. Its shield-companies are kept at a constant war-footing, arms blessed and armour sealed, so that they might translate to any threatened world at a moment's notice and give battle before the enemy has even established a foothold. Such preparation has forged a host that fights with explosive speed, hurling itself into the fray with such momentum that battles are decided in the opening moments. Slow sieges and grinding attrition are not their way; the Solar Watch strikes like a thunderbolt and is gone, the threat annihilated before it can spread.
So close do these Custodians stand to the heart of the Imperium that their presence upon a battlefield is itself a measure of how grave the danger has become. When the Solar Watch marches, it is because something has dared to threaten the Emperor's own domain, and the Castellans of the Blessed Worlds answer such trespass with the cold finality of the Master of Mankind's wrath.
Adeptus Custodes
Order of battle
The Solar Watch field the units of the Adeptus Custodes — a detachment from the roster:
Kindred formations
Other Adeptus Custodes formations
Aquilan ShieldThe first and most storied of the Shield Hosts, marching under the double-headed eagle to defend worlds Terra cannot afford to lose.
Dread HostWardens of relics and interred war machines, the Dread Host answers when the enemy's threat calls for annihilation rather than defense.
Emissaries ImperatusThe Emissaries Imperatus are the shield-host that carries the Emperor's light beyond the walls of the Palace and out into the darkness of a broken galaxy. When the Indomitus Crusade was launched to reclaim the Imperium, it was Custodians such as these who stepped forward to leave sacred Terra and fight upon distant worlds. Wherever they go they bear the authority of the Master of Mankind made manifest, and they strike with such certainty that no foe endures their opening blows.
ShadowkeepersThe Shadowkeepers are the grim wardens of the Dark Cells, the black-armoured shield-host that keeps watch over the forbidden things imprisoned in the deepest vaults beneath the Imperial Palace. Theirs is the duty of the jailer, to hold entrapped the dread entities and heretical technologies too dangerous to destroy. Should any such horror ever slip its bonds and appear abroad, it falls to the Shadowkeepers to hunt it down and drag it back into the dark.