Why were there shortages during world war 1?

Answer 1

If you mean shortages of civilian goods and food, because normal peacetime patterns of production and trade were disrupted by the war. Factories were retooled to produce munitions of war, workers left the job to go in the service, raw materials were unobtainable or difficult to find. Anything which had to travel by ship was subject to being lost to the German submarines. If you're referring to shortages of war materials at the front, such as the "shell crisis" of 1915, it was because planning had not anticipated the tremendous quantities of shells fired and had not provided for ramping up production, which was fraught with all the same problems as production of civilian goods.