Because Pilsen wasn't only well-known for brewing beer, it was also home to the massive Skoda arms factory. It played a part in WW II as well. One of the main reasons Hitler wanted to get hold of Bohemia and Moravia was the Skoda arms works.
TERRIBLE EFFECTS OF AUSTRIAN BIG GUNS.
The Exchange Telegraph Company's special Warsaw correspondent writes as follows:-
Surgeon-Major Lesghintseff, who is back from the great battle in Galicia, says that seven-eighths of the wounds were from shells. Half of these were from large-calibre shells, and the rest from field howitzers and field guns, including shrapnel shot.
"Bullets played no role," says this authority. "The rifle is the infantryman's toy. The infantryman does not fight. When the big guns have finished the fighting he occupies the trenches which they have won."
The effect the Austrian Skoda 42cm. (16.4 in.) guns, known as the "Pilseners,” is worse than the effect of the Krupp "Thick Berthas." The Skoda shells weigh 2,800 lb. (1 ton 5 cwt). Their normal trajectory is four and half miles high, and in soft ground they penetrate 20 feet before exploding. The explosion occurs two seconds after impact. The "Pilseners" are howitzers, and, except in diameter, do not resemble the Krupp 16in. mortars.
A "Pilsener" shell kills every one within 150 yards, and kills many who are further off. The mere pressure of gas breaks in the partitions and roofs of bomb-proof shelters. Scores of men who escape metal fragments, stones, and showers of earth ere killed, lacerated, or blinded by the pressure of the gas.
Men who are only a short distance away are torn asunder. The gas gets into the body cavities and expands, tearing the flesh asunder. Sometimes only the clothes are stripped off, leaving intact the boots. Of men close by not a fragment remains. The clothes disappear, and only small metal articles are found. If the shell is very near, the explosion melts rifle barrels as if they were struck by lightning. Men who disappear in such explosions are often reported missing, as there is no proof of their death."
Birmingham Daily Mail - Thursday 17 June 1915, page 6.
It sounds a truly terrifying weapon. This is what one looked like:
Those shells were enormous. It's no wonder they caused such terrible damage. They weren't even meant to be land weapons having been originally designed for naval batteries. 16.54 inch was even big for naval guns back then, with most battleships still fitted with 14 inch main armament.