With the outbreak of World War I, there was a shortage of small change coins. This was due to the fact that these coins were often made of valuable materials like gold and silver, which people wanted to hoard. To counteract this shortage, countries, municipalities, cities, and companies issued emergency money. By 1923, a massive amount of such money was in circulation, prompting Dr. Arnold Keller, the author of the first catalogs on German emergency money, to create a classification system that still serves as a reference today. The large denomination emergency money became particularly necessary from 1918 onwards, with three distinct phases of issuance. The first large banknotes were needed in the period following the end of World War I, with large emergency money circulating from 1918 to 1921. This catalog includes emergency money issues from nearly 600 issuing authorities across the entire region at that time.