Former Defense Secretary Jim Mattis was so set against President Donald Trump s idea to hold a multimillion-dollar military parade in Washington that he reportedly said hed rather swallow acid than watch it, according to a soon-to-be-released book by his former communications director.

Retired U.S. Navy Cmdr. Guy Snodgrass revealed Mattis scathing reaction to Trumps plan in his upcoming memoir, Holding the Line: Inside Trumps Pentagon With Secretary Mattis, which The Washington Post published excerpts from on Wednesday.

Trump eventually did hold a Salute to America event on this years Fourth of July, by which time Mattis (who last week turned one of Trumps insults against him into a compliment) had already left the administration.

Snodgrass book also reportedly detailed how Mattis attempted to rein in Trumps alleged attempt to screw Amazon founder Jeff Bezos by preventing the company from bidding on a Pentagon cloud networking contract.