Reconnaissance photograph of Boulogne taken by the German Luftwaffe in January 1940. The numbers indicate the following strategic points:

1) Modern harbour.

2) Wharves.

3) Floating dock.

4) Ocean railway station?

5) Main railroad station.

6) Coastal gun batteries.

7) Coastal fort.

8) Railway workshops.

9) Barracks.

10) Naval warship.

11) Naval warship.

12) Naval warship.

13) 2 x flying boats.

14) Air command station.

15) Aircraft tender.

16) Railway bridges.

17) Railway workshops.