Great Modron March

The Great Modron March, sometimes called the modron parade, was a periodic tour of the seventeen Outer Planes of the Great Wheel cosmology undertaken by thousands of modrons once every 289 years. "Every 289 years, the entire multiverse goes mad. Like clockwork."

- Kwint Stormbellow, rock gnome adventurer

Description
The March occurred every seventeenth Grand Cycle of Mechanus. A Grand Cycle was the time it took for the largest gear in the plane to turn once and was subdivided into seventeen cycles, each of which took seventeen years. Thus, the March occurred every 289 years.

Thousands of modrons participated in the Great March. The vast majority were monodrones, but the voyage also included modrons of higher rank, including hierarchs. A quinton usually led the entire effort and kept all the records of the voyage. As a consequence of the modron promotion system, a quinton was always present until the very end, as long as at least one modron survived the voyage. A hexton was in charge of defense, while a septon was tasked with ensuring that the march progressed smoothly. Four octons commanded each one quarter of the full contingent, assisted by nonatons. Decatons served as liaisons between the base and the hierarch modrons.

At least fifty pentadrones patrolled the lower ranks. Quadrones served as elite warriors, while tridrones and duodrones were tasked with herding and carrying out commands to the vast masses of marching monodrones. Since the March was not very efficient at defending itself, and due to the hostile nature of many of the places visited, only very few modrons managed to complete the voyage.

Location
The itinerary of the March included all sixteen Outer Planes of the Great Wheel and all of the gate-towns in the Outlands. Starting from Mechanus, the march departed from Regulus and entered the Outlands via the portal from Automata. It then proceeded around the border of the plane in the clockwise direction.

The Great Modron March followed a predictable pattern, moving from one gate-town to the next while in the Outlands and, once in a plane of the Great Wheel, crossing a portal to the next adjacent plane, subsequently emerging at its corresponding gate-town. The complete itinerary was:
 * Automata to Fortitude
 * Arcadia to Mount Celestia, towards the town of Heart's Faith in Lunia
 * Excelsior to Tradegate
 * Bytopia to Elysium, via Dothion through the location of the Golden Hills and through Amoria via the River Oceanus
 * Ecstasy to Faunel
 * The Beastlands to Arborea, via Krigala
 * Sylvania to Glorium
 * Ysgard to Limbo, via a branch of Yggdrasil
 * Xaos to Bedlam
 * Pandemonium to the Abyss, via Pandesmos and through the Plain of Infinite Portals
 * Plague-Mort to Curst
 * Carceri to Hades, via Undermountain
 * Hopeless to Torch
 * Gehenna to the Nine Hells
 * Ribcage to Rigus
 * Acheron to Mechanus

Activities
The purpose of the Great Modron March was unclear. Some speculated that it consisted of a periodic reconnaissance mission to ascertain the state of the Outer Planes and to report them to Primus. However, they never investigated any location, nor did they interact with anyone. They simply marched, looking at every new location they visited, and moving on. Others argued that the march was necessary to calibrate the gears of Mechanus, while another group maintained that the purpose of the March was to instill a sense of order in all the planes, even if just temporarily.

History
The demon lord Orcus, after being resurrected, sought to become a deity with the name of Tenebrous. He killed Primus and temporarily usurped his position, triggering an unscheduled Great March as an attempt to search for the Wand of Orcus. The unpredicted march, 200 years ahead of schedule, became known as the Rogue March. It caused great commotion in the Outer Planes and left several modrons stranded across the planes.

Ambran the Seeker, a half-elven paladin of Oghma from Cormyr, was sent on a mission to explore the planes of existence, according to his unpublished journal that dated from during the reign of King Azoun Obarskyr IV. Traveling with Glin, a bariaur guide hired to take him from Sigil to the Outlands, Ambran observed the start of the Great Modron March of the 13 century DR as the modrons walked out of the Automata portal.

A group of twelve monodrones and one tridrone became stranded in the Labyrinth in the Underdark following the Great March of the 13 century DR. By the late 1480s, the monodrones, having spent over 200 years, had degraded and could barely speak.

Appearances

 * Adventures
 * The Great Modron March • Out of the Abyss
 * Magazines
 * "The Plane Truth Part II: A Journey to the Outlands", Dragon #204