yes the circles appear to be navigation buoys. I'm surprised there's no indication of minefields, but possibly there were supplementary charts that covered this.

I've had to reduce the quality so the file size isn't too large, but if there's any areas you want specific detail on let me know.

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“This is a tale you will tell your grandchildren, and mightily bored they’ll be.” Lt. Gen. Brian Horrocks commander of British XXX Corps September 16, 1944 prior to Operation Market.