Washington, June 4 (RHC)-- Former U.S. Defense Secretary James Mattis denounced Trump's heavy-handed use of military force to crack down on protests and said his former boss was setting up a "false conflict" between the military and civilian society.

"I have watched this week's unfolding events, angry and appalled," Mattis wrote.

Mattis retired as defense secretary in December 2018 to protest Trump's Syria policy. He had declined to speak out against Trump, saying he owed the nation public silence while his former boss remained in office.

"Donald Trump is the first president in my lifetime who does not try to unite the American people - does not even pretend to try. Instead he tries to divide us," Mattis wrote in a statement published by The Atlantic. "We are witnessing the consequences of three years of this deliberate effort. We are witnessing the consequences of three years without mature leadership."

Mattis called on Americans to "unite without him, drawing on the strengths inherent in our civil society. This will not be easy, as the past few days have shown, but we owe it to our fellow citizens; to past generations that bled to defend our promise; and to our children."

Mattis said of the protesters are rightly demanding that the country follow the words of "Equal Justice Under Law" that are on display at the U.S. Supreme Court.  "The protests are defined by tens of thousands of people of conscience who are insisting that we live up to our values - our values as people and our values as a nation," Mattis said.

Mattis took particular issue with the use of force to move back protesters so Trump could visit St John's Church the day after it was damaged by fire during protests.

"We know that we are better than the abuse of executive authority that we witnessed in Lafayette Square. We must reject and hold accountable those in office who would make a mockery of our Constitution," Mattis said.