The last time there was a prolonged clash between Israel and Hamas, in May 2021, the conflict lasted 11 days, resulting in the deaths of about 250 people in Gaza and 13 in Israel. Yet within hours of the surprise attack launched early Saturday by Hamas against Israel, hundreds had already been killed. Hamas gunmen rolled into as many as 22 locations outside the Gaza Strip, including towns and other communities, where they roamed for hours. Gun battles continued well after nightfall, and militants held hostages in standoffs in two towns. In retaliation, Israel launched a series of airstrikes into...