Morten St George Theory

[Morten St. George]

From the Wiki on Soncino castle, the one you illustrated:

"In 1200 it was besieged several times by the armies of Milan and Brescia, and in 1283, after being destroyed by the attacks of those armies, the commune of Soncino decided to rebuild the castle. In 1312 the castle was occupied by the Cremonese army, and in 1391 by the Milanese army, using it during the war against the Venetian Republic. In the year 1426 new walls were added to raise the previous ones."

It's possible the swallowtail merlons were added in 1426 when they raised the walls. They might even have been added in the 16th or 17th century when a lot of castles were remodeled or expanded.

JP, For the purpose of our investigation, the timeline stops circa 1420, the carbon date of the VMS. Anything that happened after that is irrelevant.

Supporters of the Northern Italy theory claim that the swallowtail merlons were in use by 1420. A while back, I checked out in google.it every named castle with those merlons that I could find in image searches. I was satisfied that at least some of those swallowtails were extant in the 14th century though I could not affirm that any of them predate the fall of Montségur in 1244.

If, as you say, the swallowtails had religious or political significance, it would make sense to reinstate the swallowtails when rebuilding a destroyed castle.