With President Trump ordering steep new tariffs on imported steel and aluminum on Thursday, and with America’s trading partners threatening to retaliate, it looks as if Mr. Trump will get the trade war that he seems to want and that he thinks will be “easy” for the United States to win.

“Trade wars aren’t so bad,” he had said at the White House on Wednesday.

Which made me wonder: What trade wars does Mr. Trump have in mind?

The most prominent trade war of the 20th century was ignited by the Smoot-Hawley Tariff act of 1930, which imposed steep tariffs on roughly 20,000 imported goods. Led by Canada, America’s trading partners retaliated with tariffs on United States exports, which plunged 61 percent from 1929 to 1933. The tariffs were repealed in 1934.

Historians and economists continue to debate the extent of the damage to the global economy, but there is little disagreement that Smoot-Hawley and the ensuing trade war exacerbated and prolonged the hardships of the Great Depression. Many historians contend it also contributed to the rise of the Nazis and other fascist parties. There is almost universal agreement that no one “won” that trade war.