[DJ Taylor]

"The first phase involved the Saphir integrated with U.S. Navy forces to locate enemy submarines and pass data on to other friendly anti-submarine warfare assets. The “enemy submarine” in this case may have been the Los Angeles-class nuclear submarine attached to CSG 12.

In the second phase of the exercise, the Saphir switched sides and became part of the enemy force."

This could be an explanation of how the French sub wasn't immediately recognized as an enemy sub. It had changed sides in this simulated battle and the word wasn't adequately passed that it was now an enemy sub and not friendly.

It was simply a case of mistaken identity and not a penetration of convoy's defensive permiter by the French sub.

[moovova]

“It was simply a case of mistaken identity...”

Or, the French Saphir had a white flag lashed to their periscope.

[PLMerite]

The French submarine switched sides? Did it change its name to “Vichy”?