Ars Magica Campaigns
In the 1990s, my Berkeley gaming group ran four different Ars Magica campaigns. The following links provide access to extensive logs and other notes about the campaigns.

The Prospectus Locus CampaignMarch 1998 to July 1999 with Fourth Edition rules

Set in Iberia, beginning in 1213. This is the story of a covenant nearly destroyed by the Roman-Reconquista conflict of Iberia, and what came after. The Iberian background for this campaign was originally based on Peter Hentges' Tribunals of Hermes: Iberia book. These campaign logs are thoroughly HTMLized, feature lots of nice maps, and are the prettiest to look at. This was also our last Ars Magica game to date, as one of our three main Ars Magica storytellers (Bill) moved away following this campaign and another (Chris V.) slowly faded from our game group.
The Nature's Teeth CampaignJuly 1993 to June 1994 with Third Edition rules

Set in Novgorod, beginning in 1201. This is the story of a covenant founded in the icy cold of the Baltic, and how it made enemies and tried to conquer that region. Set in the same universe as Prospectus Locus, above (primarily by the fact that both feature a weakened magic system). These logs are only available in text format.
The Roman Tribunal CampaignApril 1991 to June 1993 with Revised and Third Edition rules

Set in Rome, beginning in 1198. This campaign ran for over two years at two different covenants and was the basis of the book Tribunals of Hermes: Rome, though the published books has some differences from the actual campaign. About the first year and a half of this campaign is recorded in logs here. This campaign ran following the short Nerius Campaign, and picked up a few plot lines from it. These logs are only available in text format.
The St. Nerius CampaignJanuary 1991 to March 1991 with Revised Edition rules

Set in Normandy, beginning in 1198. This is the earliest campaign that I have logs of. It is the story of a covenant founded in a monastery, and the attempts to make that arrangement work. It only ran for 9 weeks before dying for sundry reasons, but the important plot lines were picked up in the later Italian campaign. These logs are only available in text format.