AMBLETEUSE, France — The rising tide crept above their waists, soaking the babies they hugged tight. Around a dozen Kurds refused to leave the cold waters of the English Channel in a futile attempt to delay the inevitable: French police had just foiled their latest attempt to reach the United Kingdom by boat.

The men, women and children were trapped again on the last frontier of their journey from Iraq and Iran. They hoped that a rubber dinghy would get them to better lives with housing, schooling and work. Now it disappeared on the horizon, only a few of its passengers aboard.