So it's sorta been the norm for Americans for decades now to criticize how nicely wars are done and imagine they need to be done in a more respectable manner, regardless of how safe it'd make it for those involved.
It's also been the norm for people to get locked up when the war involves America and you're going against us.
For instance, the instant George Washington left office, John Adams immediately started enforcing the Alien and Sedition Acts and locked up his critics. While this was never immediately found unconstitutional, it was incredibly unpopular and the Federalist Party was absolutely obliterated in the subsequent elections.
Also it didn't even shut up the critics, who often continued issuing broadsides against the establishment even while behind bars. This is why Jefferson won.
Later, the Supreme Court would get a little more active. It was far from always favorable to the First Amendment.
Let's go to the Civil War.
Ever heard of
Clement Vallandigham? Probably not if you're not a nerd of some sort. He was literally exiled for being a "Peace Democrat" and openly opposing the war effort, and even ran for office in Ohio from exile, losing by a few votes (in current year it would be considered a rigged election).
But then let's get into
Ex Parte Merryman, another case involving Lincoln's rather spotty First Amendment record. Merryman, a pro-Confederate, had been locked up for his speech activities. Justice Taney of the Supreme Court, incidentally the very Justice who wrote the
Dred Scott opinion that arguably set off the Civil War, granted him a writ of
habeas corpus. Lincoln claimed he had suspended the writ, with absolutely zero constitutional authority for having done so.
Then let's go to World War I. It's easier to do this in the 20th Century because the bullshit was so much more obvious:
Schenck v. United States (1919). This is the "clear and present danger standard" that is currently rejected. It involved a criminal conviction for encouraging draft-dodging.
Things got a little better during World War II, although I'm omitting some of the more famous cases. For instance, in In
Hartzel v. United States, 322 U.S. 680 (1944), the Supreme Court overturned a conviction under the Espionage Act of 1917 (the same law at issue in
Schenck) for "anti-Semitic" and anti-war statements by the defendant.
So while I'll agree with you that criticizing war even during wartime has in fact been a long-standing tradition of Americans, locking people up for doing it also has been.
ALERT 
