MANAMA, Bahrain — The battle began soon after sundown. And for the next six hours, in air heavy with heat and tear gas, phalanxes of police officers in helmets battled scores of youths in ski masks, as customers at a Costa Coffee not far away sat like spectators.

No one won in the clashes, which erupt almost every night in this Persian Gulf state. Five months after the start of a ferocious crackdown against a popular uprising — so sweeping it smacks of apartheidlike repression of Bahrain’s religious majority — many fear that no one can win.

“This is all cutting so deep,” said Abdulnabi Alekry, an activist whose car was stopped at one of the checkpoints of trash bins, wood and bricks the youth had fashioned during the clash in August. “The fabric here was never that strong, and now it is torn.”

In the revolts that have roiled the Middle East this year, toppling or endangering a half-dozen leaders, Bahrain, an island kingdom once best known for its pearls and banks, has emerged as the cornerstone of a counterrevolution to stanch demands for democracy. While the turmoil elsewhere has proved unpredictable — the ascent of Islamists in Egypt, the threat of civil war in Syria and the prospect of anarchy in Yemen — Bahrain suggests that the alternative, a failed uprising cauterized by searing repression, may prove no less dangerous.