Medieval calendar calculator

Our sources for the history of early medieval Scotland provide a long list of dated events but, in most cases, only the year is given. A few events are dated more precisely, allowing us to look at them in relation to seasonal conditions (such as travel problems in winter) or to religious festivals (reflecting pre-Christian as well as Christian beliefs). If knowing the month seems useful and interesting, then so too is knowing the day of the week. We might be curious to find out, for instance, if a particular event happened on a Sunday, or on the feast-day of a saint. This is where a ‘calendar calculator’ makes things easy, especially if it’s a free online resource.

To illustrate this point, I’ve picked two related events from the 8th century. The source for both is an old Northumbrian chronicle incorporated into the Historia Regum Anglorum attributed to Symeon of Durham (c.1130). The context is a military campaign launched by Northumbrian and Pictish forces against the Clyde Britons in the summer of 756. Two precisely dated events are given in the chronicle.

1st August: With the Anglo-Pictish alliance having laid siege to their citadel at Dumbarton, the Britons ‘accepted terms’, presumably in a formal ceremony of submission.

10th August: The Northumbrian army, marching homeward from Govan on the Clyde, was ambushed and nearly massacred by unidentified foes.

Putting the first of these dates through a calendar calculator we learn that the Britons accepted terms on a Sunday. Not just any Sunday either, but the harvest festival known as Lammas (Old English: ‘loaf mass’). Were the Britons forced to render their grain harvest as a tribute-payment to the Picts and Northumbrians?

The ambush nine days later occurred on a Tuesday. August 10th is the feast-day of St Laurence, one of the most famous of the early martyrs, who was venerated all over Christendom by c.500. By coincidence, Laurence’s execution in Rome on 10th August 258 also occurred on a Tuesday. A saint who shares the same feast-day is Blane or Blaan, traditionally regarded as the founder of the monastery at Kingarth on the Isle of Bute in the Firth of Clyde. An old Irish martyrology calls him ‘triumphant Blaan of the Britons’. This obscure reference seems consistent with the possibility, discussed in a previous blogpost, that Kingarth eventually passed under the control of the Clyde kings. Whether the timing of the ambush in 756 had any connection with Blane’s feast-day, or with Laurence’s, is unknown, but the attacking force may have offered its prayers to one or both saints beforehand, hoping to invoke their goodwill.

Here’s a link to the medieval calendar calculator I used in this exercise. It doesn’t mention St Blane but seems to be a good reference tool for the feast-days of Latin saints.

[This post was edited on 11 February 2011 at 1.30pm BST]


6 comments on “Medieval calendar calculator

  1. Ian Malcolm says:

    This is interesting. How accurate should we expect it to be tho’?


    • Tim says:

      Good question, Ian. I generally use it in conjunction with other sources – primary and secondary – which means holy days and other key dates can be cross-checked.

  2. It works for May 20, 685, a Saturday. Bede indicates that Cuthbert had his feeling the battle was being decided on a Saturday. Likewise the calendar tells us that Ecgfrith died 6 days after Pentecost. This may suggest that he waited until after the feast of Pentecost to undertake his campaign.

    • Tim says:

      I wonder where he celebrated Pentecost? The church at Abercorn seems a possibility. From there, a journey of 4 days would easily bring him to Dunnichen by Saturday 20th, even with time spent pillaging Pictish villages en route. But maybe 6 days (120 miles at a march-rate of 20 miles per day) if the battle was further north at Dunachton.

  3. This is a jolly useful find, Tim, thankyou. The sort of thing I don’t think about enough, but may well do more if it’s easy to look up.

    • Tim says:

      The only drawback I’ve encountered so far is the ability of this neat little gizmo to keep me from doing other things.

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