Thanks to the preeminent Tarawa game designer, Paul Rivas, for the identification of this gun.
He writes:
4Nov99 (2345hrs)
I went through my military reference library and I think I found out about your "mystery gun", although I imagine by now more astute military buffs have already ID'd it for you. Anyway, the photos seem to indicate that it is a French WWI gun first used in action in 1917. It was called: Canon de155 Grand Puissance Filloux, and was a 155mm gun. It was good enough that the US military adopted it for use until WW2 as the 155mm Gun M1918M1. In French service this gun was known as the Can 155 GPF, and in 1939 there were still 449 in service. When the Germans conquered France in 1940 the guns were taken over as the 15.5cm K418(f). This would explain the German-looking steel wheels on your photographs. They prized these guns highly and used them as standard field guns and later as coastal defense artillery.
15Nov99 (0115hrs)
The wheels are definitely of German origin according to the photos in my book, and the b&w photos, although taken from another angle, look very much like your "mystery gun". They're definitely not Japanese, and most definitely NOT the infamous "Singapore" guns from Tarawa. They were mounted in steel gun turrets--not on wheels. If you want to check out my suggestion, take a look at the "WW2 Fact Files" softcover series entitled "Heavy Artillery" by Peter Chamberlain & Terry Gander, published by Arco Publishing, copyright 1975. The gun can be found on pages 17-18 (Fr) and page 51 (US). I have eight of the books--lot of stuff on Japanese weapons many of which were used on Betio.
The side of the gun reads "Soyez Bons Pour Vos Fabins."
The gun was photographed in the town park in Edgemont, South Dakota.
Email - Jonathan.E.Stevens@wheaton.edu
copyright 1998 Wheaton, Illinois
Updated March 25, 2000