Democrats won an unexpected victory Tuesday when legislation to halt the Iran war cleared an initial hurdle in the Senate — a vote that strengthens their hand in the increasingly fractious debate over the conflict. Critics of the military operation took advantage of a shorthanded Republican conference — three GOP senators missed the vote — resulting in a 50-47 decision to force debate on a rebuke of President Donald Trump. War opponents gained another GOP defector in Sen. Bill Cassidy. The Louisiana Republican, who voted to convict President Donald Trump in the wake of his second impeachment over the Jan....