Somebody is filling the mailboxes of Washington reporters and investigators with a report that bluntly claims retired Gen. James Mattis, President Trump’s “mad dog” first Pentagon chief, authored the famous New York Times hit piece “Anonymous” and a longer book, A Warning.

The 33-page report, titled, “Disclosure of Anonymous: 2020 election,” suggests that the goal of the attacks by Anonymous was to set Mattis up for a 2020 presidential bid. It looks somewhat authentic and even includes blacked-out sections, but a source with a knowledge of who Anonymous is laughed it off. Mattis has also denied it. …