These words are the official slogans of the Party, and are inscribed in massive letters on the white pyramid of the Ministry of Truth, as Winston observes in Book One, Chapter I. Because it is introduced so early in the novel, this creed serves as the reader’s first introduction to the idea of doublethink. By weakening the independence and strength of individuals’ minds and forcing them to live in a constant state of propaganda-induced fear, the Party is able to force its subjects to accept anything it decrees, even if it is entirely illogical —for instance, the Ministry of Peace is in charge of waging war, the Ministry of Love is in charge of political torture, and the Ministry of Truth is in charge of doctoring history books to reflect the Party’s ideology.
That the national slogan of Oceania is equally contradictory is an important testament to the power of the Party’s mass campaign of psychological control. In theory, the Party is able to maintain that “War Is Peace” because having a common enemy keeps the people of Oceania united. “Freedom Is Slavery” because, according to the Party, the man who is independent is doomed to fail. By the same token, “Slavery Is Freedom,” because the man subjected to the collective will is free from danger and want. “Ignorance Is Strength” because the inability of the people to recognize these contradictions cements the power of the authoritarian regime.
Emphasis is mine.
The application to current events is scarily dead on.
"Freedom Is Slavery” because, according to the Party, the man who is independent is doomed to fail."