Hiroo Onoda was a soldier in the Japanese army who ended up fighting World War II for longer than anybody else on Earth. 

Staying true to his orders to conduct guerilla warfare in the Philippines, he remained in the mountains for years – first with a group of soldiers, and then alone – planning and conducting attacks, as well as stealing food from local villages down below. Several efforts to contact Onoda and his fellow soldiers failed, including dropping leaflets to the group informing them that the war was over, with surrender orders signed by General Tomoyuki Yamashita.

"The leaflets they dropped were filled with mistakes so I judged it was a plot by the Americans," Onoda explained in an interview in 2010, many years after he realized his mistake.

Japan began dropping photos of loved family members to the group to prove that they weren't being duped, but unfortunately Onoda believed that this too was a trick. Eventually, after his final companion was killed by police two years earlier in 1972, an explorer searching for him was able to convince Onoda that the war was over, by bringing back a superior officer.

He fought World War II for 29 years longer than the war actually was. But, if a US custom is to be believed, he is not the last person that is still on patrol. The US Navy even tries to contact them every year.

According to the US, 374 officers and 3,131 men who fought in World War II are officially still "on patrol" 77 years after the war ended. The soldiers were all aboard US submarines that never returned to the US. It is a tradition to list those on submarines which don't return as "still on patrol" or "on eternal patrol", though of course the reality is that the submarines were sunk long ago.

Nevertheless, sailors on communication hubs send out a message to these submarines once a year around the Christmas holidays, also as a tradition.

"We shall never forget that it was our submarines that held the lines against the enemy while our fleets replaced losses and repaired wounds," a plaque dedicated to the sailors "still on patrol" reads.

"I can assure you that they went down fighting and that their brothers who survived them took a grim toll of our savage enemy to avenge their deaths."