A text from one such blood chit translates as follows:

Cloth maps, charts and blood chits of World War II.

Now that these modifications are part of the official issue, only "Blood Chits" and other internal linings are added by the aircrew themselves.

Many US flight crews that flew over Asia had their "blood chit" sewn to the back of their flight jackets.

Some units added the blood chit to the flight suit while other units gave the blood chit only for the specific flights.

He patted his jacket where the four blood chits reposed safely, absolving him of all responsibility if anything happened to Messrs. Smith, Jones, Robinson, or Brown.

The idea of blood chit originates from 1793 when French balloonist Jean-Pierre Blanchard demonstrated his hot air balloon in the USA.

Blood chit is a notice that is carried by the military, usually aircraft personnel, that displays messages aimed at the civilians that ask them to help the servicemember in case they are shot down.

Into a specially prepared nylon "sortie" wal- let they placed their military identification cards, some cash, credit cards, and traveler's checks-these were many times more valuable than the "blood chits" used to buy assistance during earlier wars.

When the USA officially joined the war in 1941, flight crew survival kits included blood chits printed in 50 different languages that sported a US flag and promised a reward for a safe return of a pilot.

Some jackets (famously, those from the China Burma India Theater, and of the Flying Tigers) had a "Blood chit" sewn on the lining or outer back, printed on cloth, which promised certain rewards to civilians who aided a downed airman.

Examples of blood chits issued to British RAF personnel in India in the 1940s are printed on thin sheets of silk cloth measuring 20 by 11 inches (about 50 x 30 cm); they have the Union flag printed at the top left, and the following text in English and French alongside it: