Two modern Waterloos: Brexit Boris and Impeachment Don

British Prime Minister Boris Johnson and American President Donald Trump are facing 21st century political variants of Waterloo, the monumental battle that Wellington won and Napoleon lost. For Johnson, it is Brexit. For Trump, it is impeachment. Both are virtually inevitable.

Johnson's first week in office has certainly set his government on a course for leaving the European Union on Oct. 31 with or without an agreement. His Cabinet has been selected for this journey that many in Britain believe is a kamikaze mission.

Johnson does, however, have three options. The first is to leave the EU, as he says, "come hell or high water." The second is to do a Boris and true to his prior history cynically reverse course dusting off the flawed agreement negotiated by his predecessor Theresa May, adding a few "dealmakers," declaring victory and leaving with a document he could claim as an earlier prime minister did of bringing "peace in our time."

Or, Johnson could take a hugely risky gamble and call a "snap election." If Johnson won a majority or a coalition he could command, Brexit on Oct. 31 would be guaranteed. Suggesting this option is the appointment of a campaign team in No. 10 headed by senior adviser Dominic Cummings, the architect of Brexit and called a "professional psychopath" by former Prime Minister David Cameron. If Johnson loses, oh dear.

Johnson has no other choices in the 90-plus days until Oct. 31. While Brexit remains the most pressing issue confronting Johnson, the Persian Gulf and Iranian seizure of two British-flagged tankers several weeks ago could be explosive. Given the decline of the British military and a Royal Navy lacking enough "gunboats" to conduct gunboat diplomacy, a crisis with Iran is the last thing the new government needs. And no doubt, other unpredictable issues and events will intervene, including how the prime minister controls his mercurial personality.

While Trump called last week's testimony of special counsel Robert Mueller vindicating and exonerating, because the Democrats will soon have no alternative, impeachment could dominate his remaining time in office. The reason is that impeachment will be the Democrats' only chance to bring down Trump because it is the only means of producing sufficient evidence and proof of wrongdoing. The hearings of former Trump attorney Michael Cohen and Mueller changed no one's minds about presidential "high crimes and misdemeanors."

The White House has narrowed congressional options by refusing to provide records and data subpoenaed by the House, including Trump's tax returns, in direct violation of the law. Hence, over the summer, Democrats ambivalent over impeachment proceedings because of not securing a Senate conviction, are likely to conclude that the only way of uncovering relevant facts is through these hearings. They are correct. Any White House would be unhelpful in providing potentially damaging material such as the Watergate tapes. And Trump believes that because the Senate would never convict him, acquittal would rebound against Democrats and ensure his re-election.

Comparisons with Watergate and a Republican Senate that would have convicted President Richard Nixon if impeached are misplaced. For one, who are today's Sens. Howard Baker ("What did the president know and when did he know it?") and Sam Ervin? And no equivalent to the Vietnam War has so shaken the trust of the American public in government to oust a sitting president without unimpeachable proof of a serious crime.

The two greatest democracies of the 20th century have become so incapacitated in the 21st. Perhaps Johnson will emulate Wellington and win the Waterloo battle over Brexit. Yet, no one at No. 10 seems to have thought through the consequences of what happens on Nov. 1 if Britain exits with a hard landing and how it will deal with the EU on the unresolved and potentially unresolvable trade, financial, business and legal issues.

If Trump believes impeachment will be his Waterloo, he may get his wish. But if the trial uncovers truly damaging evidence and proof of wrongdoing, even if the Senate refuses to convict on partisan lines, the victory will be Pyrrhic. And while the Justice Department's Office of Legal Counsel opinion is that sitting presidents cannot be indicted, the debate over Trump's future and what happens when he leaves office will dominate politics.

Impeachment hearings could also uncover no new "smoking guns" that, while not fully exonerating, surely will acquit the president, support his re-election and possibly place the House under Republican hands. But no matter how Brexit and impeachment turn out, the future for the United Kingdom and the United States will surely be decidedly more chaotic, corrosive and grim.

Harlan Ullman is a senior adviser at the Atlantic Council. His latest book is "Anatomy of Failure: Why America Has Lost Every War It Starts." Follow him @harlankullman.