The two are related, as the decline in the number of students studying foreign languages ​​can be directly linked to the xenophobia of World War II which, in some cases banned the teaching of foreign languages. William Riley Parker directly connects the two, arguing that the decline in the number of students studying a foreign language was the result of the phobia of Germans that swept the country in the 1940s. Thus, to fully understand the literature on German politics foreign languages, the different threads of history: the policy of teaching foreign languages, the maintenance of immigrant languages ​​and the policy of English only must be studied.