story
In the beginning Assange tried to vet the leaks he published. He contacted the US over the Manning leaks to go over them so he could publish without risk, the US refused.
So Assange set up a huge team of journalists to comb through the documents to see what was safe to publish. One of those journalists working for The Guardian proceeded to publish the key to the entire database, ensuring everything was leaked
Shortly after, he ends up in embassy and was unable or unwilling to do similar things.