In the Factol's Manifesto, it states that the next Modron March is due in "about a year". It also gives Hashkar's current year of rule as 127. So presumably the next Modron March would come sometime in 128... but I know that Orcus became Tenebrous, killed Primus, and sent the Modrons out early, so that throws the whole thing off! (I don't have the book the Great Modron March, so I'm not privy to whatever chant is there...) After a new Primus took over, did they go back to their old March schedule, or did they count the March Orcus sent 'em on? Oy, veh...
What dates do the Modron March take place?
Sat, 2007-11-17 12:43
#1
What dates do the Modron March take place?
Wed, 2007-11-21 09:42
#3
What dates do the Modron March take place?
The Modrons march once the great cog of Regulus (and I think the same on the Modron Cathedral rests upon) makes one full revolution.
This occurs every 14 cycles with one cycle being 14 planar years.
Thus the Modrons march every 196 years.
Whether they reset for the Tenebrous thing or ignore the anomoly, I feel, is best left to individual DMs.
Wed, 2007-11-21 19:38
#4
What dates do the Modron March take place?
How many years early did the Tenebrous March happen? Because if it was only a few years, the issue might have come up and thus must be, at some point, covered in canon.
Wed, 2007-11-21 20:34
#5
What dates do the Modron March take place?
This occurs every 14 cycles with one cycle being 14 planar years.
The magic number is 17, actually. The number isn't arbitrary - it's one year for each Outer Plane.
So a Grand Cycle happens every 289 years.
According to The Great Modron March, the last Modron March happened 'just over a hundred years ago." That adventure took place in Hashkar 129 (two years after the time The Factol's Manifesto was set), so the last March must have happened in Hashkar 28 or 29. It would have been normally due about Hashkar 317, so it was about 188 years early.
Thu, 2007-11-22 01:40
#6
What dates do the Modron March take place?
As a counterpoint, Planes of Law: Mechanus states "Once every cycle (when all the cogs of Mechanus complete one full turn, approximately every 17 years), the modrons marshall a vast army and march forth from Mechanus to tour the Great Ring."
That'd make a Great March occur much more frequently than every 289 years.
Thu, 2007-11-22 02:05
#7
What dates do the Modron March take place?
Yeah, early on it was always every 17 years. The Factol's Manifesto and David "Zeb" Cook's The Plane Truth articles in Dragon magazine and, I believe, A Player's Primer to the Outlands all say the same thing. It was, in fact, a big deal in The Factol's Manifesto that Factol Pentar was preparing for the next March so that she could be the first Doomguard factol to stop it. Obviously, if the March wasn't due for 200 years, it isn't reasonable that she (as a human whose faction eschews life-extending magics) would be expecting to see it (unless she was in cahoots with Tenebrous?).
They retconned it for The Great Modron March because it didn't seem very dramatic for the March to happen only a few years short. From then on, it was assumed that the number was 17 squared, not merely 17. And the Pentar subplot was never mentioned again.
Mon, 2007-11-26 14:09
#8
Hmm
Thanks! Lots of useful info here... 
The question was raised but never answered in canon, but it's definitely something that should be decided upon by Planewalker. I'm still a bity fuzzy how often the thing happens in terms of actual years. Regardless, I would vote that the march continues as if the disruption never occurred and the famous march happened on time. My reasoning is that the Modrons are ultra-conservatives, averse to change unless planned long in advance.