When was the Service flag first flown?

The Service flag was first displayed in the front windows of homes during World War I to signify a son or husband serving in the Armed Forces. The flag quickly became known as the "son in service flag" with each blue star indicating one family member. During World War II, the Department of War issued specifications on the manufacture of the flag as well as guidelines indicating when and by whom the Service flag could be flown or the Service Lapel button could be worn (an example of the flag can be seen hanging in the window of Mrs. Ryan's house in the movie Saving Private Ryan).