Serving as a companion piece to the hugely acclaimed HBO World War II miniseries Band of Brothers, The Pacific is based on a true story – but that doesn't mean absolutely everything in it is true. The series follows the 1st Marine Division across campaigns against the Japanese forces occupying the islands of the Pacific Ocean. Based primarily on Robert Leckie's memoir Helmet For My Pillow, and Eugene B. Sledge's book With the Old Breed, The Pacific strives to depict the grim reality of warfare in the Pacific Theater as accurately as possible. But with the wealth of source material that had be condensed into a 10-episode series, there are inevitably some details from the true story that are left out.

https://screenrant.com/pacific-show-true-story-details-missing-information/