Through the history of mankind there was necessity to use safe exchange and protection of important information. People tried to hide their messages making them invisible and unable to understand. Cryptography developed from skills which rare people used for century and became a science. In this graduate thesis we have been dealing with transposition cipher system ADFGX and ADFGVX used my German Army during the World War I. The choice of letters ADFGX was to reduce the number of mistakes while sending messages because in the Morse Code these letters have the smallest resemblance. After three months of using code ADFGX got one more letter V to be able to send numbers. The first one to crack codes was French Colonel George Jean Painvin. The first two chapters give basic information needed to explain and understand the work. The importance of cracking ADFG(V)X cipher system and its influence on World War I’s outcome have been shown. This work explained special cases dealing with ADFGVX cipher system and also the common procedure which don’t depend on speciality of caught cryptograms.