Official abbreviation: F.H.T.
Instituted March 11th 1953 by King Frederik IX.
The oak leaf device was instituted 8. November 2005 by Queen Margrethe II.
Awarded to any man or woman after 25 years of consecutive service in the Danish Defence (Ministry of defense, military schools, etc, not part of either the Navy, Army or Airforce), after their 20th birthday.
After 40 years of service, a Gold Oak-leaf will be added to the ribbon.
Design: Worn in a red ribbon with a wide white centre stripe. The medal is in silver and the obverse shows the monogram of King Frederik IX.
Other information: Personnel eligible for the Fortjenstmedalje, will get that instead of the 40 years Long Service Medal.
Official decree (Danish)