Complex sentence: During 1933 and 1934, after Adolf Hitler became Chancellor of Germany, the "Reichswehr" began a secret program of expansion, which finally became public with the formal announcement of the "Wehrmacht" in 1935.
Split into simpler sentences: During 1933 and 1934, after Adolf Hitler became Chancellor of Germany, the "Reichswehr" began a secret program of expansion. The secret program of expansion, finally became public with the formal announcement of the "Wehrmacht" in 1935.