Islamic State Helps Reshape Obama's Second Term

When President Barack Obama speaks to the nation on Wednesday, he won't merely be discussing his strategy for taking on the militant fighters of the Islamic State. He will be acknowledging, tacitly, that he is overseeing a second term radically different from the one he imagined.

In that sense, Mr. Obama has become only the latest American president to learn that history doesn't afford the occupant of the Oval Office the luxury of choosing what kind of presidency he gets to conduct. A president has many powers, but the power to fully control the tides of history as they form around him isn't one of them. Like the rest of us, he often is left to respond to them.

This appears to be a painful truth for Mr. Obama, which helps explain why he has been so obviously reluctant—and so dangerously slow, his critics say—to embrace the challenge of confronting the resurgence of radical Islamic forces in Iraq and the dangerous cauldron of