During their defense of Saipan & Tinian the Japanese had numerous coastal defense batteries. Some were comprised of British made 150mm guns purchased in 1906. Most such batteries were easily detected and destroyed prior to the landings. Usually located on points, and unable to engage targets once inland.
An episode in a "short list" of successes for such emplacements.
One battery of three such weapons located south east of Tinian Town, were so well concealed that they had not been detected until they opened fire on J-1. During the pre-landing bombardment this battery opened fire on the USS Colorado (BB), scoring 22 hits, and on the USS Norman Scott (DD-690) achieving 6 hits. The Colorado suffered 43 dead (10 Marines), and 198 wounded (32 Marines). While the Norman Scott lost 19 dead and 47 wounded.
These guns had inflicted enough damage that both ships were withdrawn from the gun line for repairs.

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"Danger Will Robinson!"