challenge and response
During Operation Overlord soldiers were trained to use a "challenge and response" system in order to identify friendly forces in situations were they could not make visual contact.
Captain Miller's Ranger squad used this system while passing through the town of Neuville during their search for Private James Ryan.
First Army Passwords
| Day | Challenge | Password | |
|---|---|---|---|
| June 6 | D-Day | flash | thunder |
| June 7 | D+1 | thirsty | victory |
| June 8 | D+2 | thirsty | victory |
| June 9 | D+3 | thirsty | victory |
| June 10 | D+4 | weapon | throat |
| June 11 | D+5 | weapon | throat |
| June 12 | D+6 | weapon | throat |
| June 13 | D+7 | wool | rabbit |
| June 14 | D+8 | wool | rabbit |
| June 15 | D+9 | wool | rabbit |
Fact vs. Fiction
The proper order of the challenge and response is reversed in the film. The proper challenge on D-Day would have been "flash," the password "thunder," and the countersign "welcome."
The challenge and response words were changed every three days in the First Army, which further confuses the use of this system in the film, since the Rangers were in Neuville sometime between the 9th and 13th of June. The 101st paratroopers would not have been using flash/thunder/welcome by that time.