Wikipedia has the following definition of a redan as it applies to GCA:
A redan hole or redan is an aspect of golf course architecture commonly associated with golf architect Charles B. Macdonald. The term alludes to the "redan" type of fortification. Specifically, a redan hole should have a green where the front angle is a "V" shape and which slopes downward and away from the point of the "V", and consequently from the golfer playing to the green from the tee or fairway.
Most if not all redan holes are flanked by a pair of deep bunkers, deep enough to be obscured from the green, and slope either to the left or the right. The original "redan" is the 15th hole on the West Links in North Berwick, a fearsome 192-yard par 3 which requires an accurate tee shot to an elevated, sloping green invisible from the tee. Golf architects around the world have created holes based on this signature challenge of the famous Scottish course.
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Do you think the definition is correct?
The definition of a redan
fortification is correct but the way the author applies it to CBM's Redan golf holes seems a bit of a stretch. I wonder if the original at North Berwick actually got its name from the first hill, visible and just over half-way from the tee, as the left side of that is distinctly redan-shaped.
The irony, of course, is that this landform, which makes the tee-shot blind, was dropped from CBM's copies, as what he especially admired about the NB hole was the narrow tableland, tilted a little from right to left, with a deep bunker on the front side, approached diagonally.
So all the American Redans, though they may be better golf holes than the North Berwick original, don't have a 'redan'.