Throughout Mariupol, Russian workers are tearing down bombed-out buildings at a rate of at least one a day, hauling away shattered bodies with the debris.

Russian military convoys are rumbling down the broad avenues of what is swiftly becoming a garrison city, and Russian soldiers, builders, administrators and doctors are replacing the tens of thousands of Ukrainians who have died or left.

Many of the city's Ukrainian street names are reverting to Soviet ones, with the Avenue of Peace that cuts through Mariupol to be labeled Lenin Avenue. Even the large sign that announces the name of the city...