The longest serving but least documented, dogs have been used in warfare since ancient times (7th Century BC) as their obedience, dedication, and loyalty combined with their speed and agility make them an invaluable asset. Their formal enrolment started in World War I and now dogs are specifically trained and selected.
Many of the modern day agility obstacles are based on tasks carried out by war dogs. A third of all dogs used in WWI were pets donated to the war effort by their owners. War dogs have been search dogs, sniffing for mines and explosives, messengers carrying orders and supplies to the front line, sentries, patrol dogs, and search & rescue dogs.