You're full of shit. They never said any such thing about the Germans. They started immigrating here at least 200 years ago.
You need to educate yourself, dummy.
During World War I, U.S. Government Propaganda Erased German Culture
This week marks the centennial of U.S. entry into World War I, a conflict that shattered empires and cost millions of lives. On the American home front, it made this country less culturally German.
Today, when the question of loyalty of immigrants has again become contentious, what happened a century ago has special relevance. World War I inspired an outbreak of nativism and xenophobia that targeted German immigrants, Americans of German descent and even the German language.
It was a remarkable reversal of fortune. Germans were the largest non-English-speaking minority group in the U.S. at the time. The 1910 census counted more than 8 million first- and second-generation German-Americans in the population of 92 million.
"Hans Kuhnwald, the concertmeister of the Cincinnati Symphony Orchestra, was interned; the German language was forbidden; the German-American press was heavily censored; libraries had to pull German books off the shelves; German-American organizations were targeted," Schade says, "and what happened, of course, is the German-Americans considered themselves to be good Americans of German extraction, several generations removed from the old country."