The study regarding usability of bow slits in fortified castles and their military benefit is more or less finished.

Inspired by the visit of some Scottish castles with impressive high slits during a research seminar of Dr. Joachim Zeune BINSY performed some practical trials regarding the usability of such slits in German castles of the 13th and 14th century with long bows and crossbows in the years 2009 and 2010. By this occasion more than 50 slits of castles in Alsace and Palatinate were analyzed, surveyed and filed in a database.

The „instruments“ for the trials – two self long bows of maple wood and ash wood and two cross bows of oak and cherry wood with steel bows were reproduced by Rüdiger Bernges from BINSY according to medieval templates.

As an object for the trials some appropriate castles in Alsace (France) had been chosen: in the first place the Spesbourg castle near Andlau, additionally Ortenberg, Birkenfels, Hoh-Andlau, Wangenbourg und Landsberg. Analyzed as well were the castles Gräfenstein and Neu-Leiningen in the Palatine Forest (Germany) and additional Schönburg castle in Oberwesel and Pfalzgrafenstein near Kaub, both on the river Rhine.

The results were astonishing. Some castles with their slits allow convenient bow shooting with appropriate shooting angles to the left and to the right. The shooting angles using the crossbows were always limited to a straightforward shot through the wall because of the length of the bow. In this case cross slits were NOT helpful to enlarge the shooting angles as supposed before (tested in the keep of Wangenburg castle).

Some slits, e.g. those of Birkenfels castle, were not usable at all. The openings of the slits were too narrow and too low for using the bow in a secure and effective way. Only for a straightforward shot with the crossbow these slits could be used. The presumption of Dr. Zeune, that many castles only have slits for deterrence, could be proved as true. Once again very interesting was Ortenberg castle. Here the research shows that the building master has planned and implemented the slits very systematically and with great effects. The slits cover systematically jeopardized areas on the side of possible attacks.

Interesting as well were the results about the supposed security of a defender behind his slit. The practical trials with the long bow show that even the not-well-trained bow shooters from BINSY were able to shoot from outside the walls through the slit into the inner embrasure. Well-trained bow men could “keep a slit blind” for a while with permanent shooting - as the trials showed.

Extensive analyses, plans and measures of the slits as well as detailed results are published in diverse media: the scientific magazines Burgen und Schlösser (DBV), ARX (Südtiroler Burgeninstitut) and the periodical of the Interessengemeinschaft Historische Armbrust (Jens Sensfelder). Detailed information regarding the slits can be found in the following BINSY database: