How does a medieval moated castle work?

Thank you very much for your fascinating questions.

Essentially, it was in the 10th and 11th centuries that the first important noble families began to fortify their residences. On the one hand, this was an attempt to secure their property. On the other hand, these fortified noble residences also served as symbols of prestige. The castle was intended not only to protect against external enemies, but also, quite certainly, against their own subjects. These were generally exploited quite ruthlessly.

From the hilltop castle …

Hills and steep rocky ridges offer obvious protection. This is the most common choice of location for a nobleman’s castle. Hilltop castles had the advantage that they were not only well protected but were also usually visible from afar. The lord of the castle effectively “marked” his territory with such structures. However, there are also castles – often particularly early structures – that were situated closer to settlements. As topographical protection was usually lacking in such locations, artificial mounds – known as motte castles – were built, upon which a fortified tower was then erected. The Büchel in Zunzgen (Canton of Baselland) is one such motte.

... to the moated castle

And then there are also noble residences in the valley lowlands, which were protected by moats. The idea of building a fortified castle by the water is an ancient one. At Lac de Paladru (Isère department, France), there is such a structure – built entirely of wood – which dates back to around 1000 AD. The famous Chillon Castle on Lake Geneva may have similarly early origins. If there is no lake, it is possible to protect the complex with moats. The “Weiherhaus” near Gelterkinden, which you have read about, is one such example. We suspect that the nearby Eibach was dammed to maintain a constant water level.

There were a considerable number of such “Weiherhäuser” in the Basel region (and beyond). Because they were so conveniently situated in the valley, they remained inhabited even after the old hilltop castles had long since fallen out of favour and the need for protection had become increasingly secondary. Water castles such as Binningen, Bottmingen or Pratteln (to stick with examples from the canton of Baselland) have remained intact to this day.

A glimpse into the past

However, these castles no longer reflect their original, medieval form. That is why archaeological finds such as those at Gelterkinden, which reveal their condition in the 14th/15th centuries, are so important for archaeological research. It appears that the structure in Gelterkinden was a massive, rectangular building – certainly multi-storey – with metre-thick rubble stone walls, which was almost directly surrounded by a moat. It was 14 metres wide, probably at least 20 metres long, and had a tiled roof. However, the full floor plan is not yet known.

Advantages and disadvantages of a moated castle

I do think that in summer, one would have had to contend with mosquitoes in such a ‘Weiherhaus’. But as the fields were still much less regulated in the Middle Ages and there were many wetlands and marshes, this probably wouldn’t have been particularly noticeable.

"Just imagine having to endure hours in freezing cold whilst wearing a suit of iron armour ;-)"

Your question as to whether the house lay unprotected in winter, when the moats were frozen over, is entirely valid. But on the one hand, the solid stone construction naturally offered a certain degree of protection even without the ditches (after all, it already had to withstand firearms in the 14th and 15th centuries). And on the other hand, a certain truce also applied during the winter months in times of war and feuding. After all, sub-zero temperatures were a tough challenge for attackers too. Just imagine having to endure hours in a suit of iron armour in the freezing cold ;-)