During the summer and fall of 19 forty four, the navy built massive bases on each of the captured islands of the marianas. The biggest base contained the largest airports in the world. That was on tin, six runways the equivalent of three boulder dams worth of concrete. And when they were finished, the military began flying in brand new b 29 bombers,. Their final base was no longer a mystery. Four thousand miles farther west, with only one re fueling stop on the way, lay the island of sipan. Less than four months before, it had still been in the hands of the japanese to head up the newly created b 29 strike force known as the 20. First