A commemorative envelope marking the ten-year anniversary of the start of PLA Navy escort missions. A set of 32 envelopes was released on Wednesday, December 26, 2018. (Photo: Ministry of National Defense)

Stamped with a postmark on the day they were issued, on the front of the envelopes are photos showing scenes of the navy's escort missions, alongside special edition stamps. On the back of the envelopes, details of the escort missions are printed in both Chinese and English.

A commemorative envelope issued by the PLA Navy on Wednesday, December 26, 2018 shows the navy's first escort mission. (Photo: Ministry of National Defense)

On December 26, 2008, the PLA Navy set off on its first ocean escort mission in accordance with United Nations Security Council resolutions.

Over the decade that has followed, the navy has dispatched 31 escort formations on 1,198 missions involving 100 submarines, 67 ship-borne helicopters, and more than 26,000 sailors.

These missions escorted more than 6,600 ships, rescued more than 70 ships in danger, and captured three pirates.