 -- The U.S. military says it has recovered and used "massive amounts" of intelligence materials from retreating ISIS militants in the city of Manbij, Syria, a town the Pentagon describes as one of the terror groups last connecting points to it's stronghold of Raqqa.

"We think this is a big deal," Col. Christopher Garver, a spokesman for Operation Inherent Resolve, told Pentagon reporters in a video briefing from Baghdad today.

Garver said coalition forces battling ISIS have gathered over 10,000 different items holding valuable information, such as thumb drives, laptops, textbooks and notebooks from the battlefield.

Over four terabytes of data was gleaned from the digital devices, Garver said. "We're learning about how they ran Manbij as a strategic hub," Garver said, calling it an orientation center for foreign fighters just joining ISIS. "As foreign fighter would enter, they would screen them, figure out what languages they speak, assign them a job -- and then send them down into wherever they were going to go, be it into Syria or Iraq, somewhere,” Garver said.

So far they have not uncovered any evidence, in this data, of fighters being launched to Europe or further west, Garver added.

He said they also found textbooks that were rewritten to reflect the teachings of ISIS.

The town of Manbij is, for now, still a heavily contested area. Over the course of the past few weeks the U.S.-led coalition has conducted more than 520 airstrikes in the area and anti-ISIS forces have the town surrounded on the ground.