The German Shepherd is often called an Alsatian because that's is where they originated in Germany. Many Germans still call them Deutscher Schaferhund mostly because of their original function as a sheepdog but the breed is not very old and was actually developed from a variety of sheep herding farm dogs in the mid to late 1800s. In 1899 Max von Stephanitz, who was a German cavalry officer, was president of the first German Shepherd association in Germany. Since then German Shepherds have turned up all over the world and they made it to the USA as early as 1908 where they were popular with the organizations such as the Red Cross, the police and as guard dogs.
This was generally because they are very loyal and courageous dogs and they are very intelligent and able to retain specialized training for an extended amount of time. With a bad temperament these dogs can be a disaster. They are highly territorial and will know and recognize their people and home by about four to six months of age. This is when their protective loyalty starts to show itself!
They have proved a very popular breed over the years for use in both the police force and as guard dogs for homes and security companies. They have a very acute sense of hearing which means that they are invaluable to anyone wanting to protect either themselves or their property.