Caliber | Ordinary concrete | Reinforced concrete | ||
---|---|---|---|---|
2km | 10km | 2km | 10km | |
40cm | 7.5 | 4.9 | 4.5 | 2.9 |
20cm | 4.0 | 2.6 | 2.5 | 1.6 |
15cm | 3.0 | 2.1 | 1.7 | 1.1 |
IJA estimated US landing gun fire in a few case study. IJN tested warship gun power at Kamegakubi in Oct to Nov 1944. The table shows the result.
Troops of defending Okinawa had to give up on shore combat. The troops made long caves or tunnels in the side of hills or cliffs.