Turkish citizens are wildly optimistic about the invasion of Syria that began Oct. 9. President Recep Tayyip Erdogan’s decision finds broad support within Turkey, including from all the major opposition parties except the pro-Kurdish People’s Democratic Party. The incursion is understood domestically not only as a measure to protect the country from the Kurdish forces Mr. Erdogan calls “terrorists,” but also to affirm Turkey’s status as a power; Ankara no longer must bow to the wishes of Washington, Berlin or Moscow.

Then...