Whatever one thinks about keeping an eye on suspicious immigrants during times of conflict, it's nothing new. Except that in the following case, it wasn't even an immigrant; it was a native-born American, and it was the British who were suspicious. After all, a hundred years ago today, the US wasn't even at war. And one race-car driver was thinking maybe that needed to change. Even though he was being followed because the English thought Edward V. Rickenbacher was German.
His background really was German, but not recently. His parents had come to America from Switzerland and Eddie was born in Ohio. Lots of people in America had German names. However, another big racing star was a real German, and Rickenbacher's name had been put together with his, saying how proud the Kaiser must be, and a Los Angeles reporter made up a story about how he was actually Baron Edward von Rickenbacher trying to prove himself in America to his strict Prussian father. (Fake news isn't new either....)
So at the end of 1916 Rickenbacher went to England to work with a motor company, but the English had heard this rumor (rumour?), strip-searched him, and wouldn't let him into England for many days. Eventually most of his interviewers realized he was not a spy, and he was able to work in England, but he got more and more convinced that the US should be in this war, and that he wanted to fly for the Allies.
There was reason to worry about German efforts to demoralize and destabilize the Allies. For instance, Germany would shortly send a poison pill named Lenin back to Russia. German saboteurs in America planted explosive devices in ships, formed trade unions among munitions workers to get them to go on strike, and tried to get Mexico and America to fight each other so America wouldn't join the war in Europe.
As tensions escalated, in early February 1917 Germany announced that Americans abroad had five days to get home. So Rickenbacher returned to the US and used his racing money to travel across the country giving talks about why the US should be in the war. Crowds came out to hear the racing celebrity. But it wasn't until he reached Los Angeles that a British agent introduced himself and said that he was finally satisfied that Rickenbacher was a loyal American.
Of course this story is about Eddie Rickenbacker, the American Ace of Aces. The spelling of his name got changed, in a roundabout way, by the same media circus that caused the confusion to begin with. He happened to write his name with two k's once, and the newspapers picked it up, announcing "Eddie Rickenbacker has taken the Hun out of his name!" So then all the rest of his family had to spell it that way too, and that is why there are now Rickenbacker guitars.