I've read that Belgium, along with the other Allies, had no mortars at the outbreak, but this pic shows some pre-war examples at a demonstration at the training camp at Brasschaet. It must be round about 1910, give or take a couple of years. They're described as mortiers de 12, and although they look like museum pieces now, they must have been state of the art. From the uniforms, it looks as if they are being trialled by men of the Fortress Artillery.
"Sometimes things that are not true are included in Wikipedia. While at first glance that may appear like a very great problem for Wikipedia, in reality is it not. In fact, it's a good thing." - Wikipedia.
These do indeed appear to be fortress weapons. Note they have sliding breach blocks; likely a Krupp product. In actuality, they are howitzers I suppose. The German practice of refering to howitzers of greater calibre than 15cm as "mortors" apparently was carried over in the photo description. Thanks for the pic.
Mortar is used frequently prewar for positional Howitzers - ie those not cabable of being fired from their transport carriage. There is a Schnieder 15cm (prob 155mm) in this class in Serbian service. This has caused no end of confusion at times.
