What significant military decision was revealed by Hitler in March 1935?

The correct answer highlights a pivotal moment in the remilitarization of Germany, revealing that in March 1935, Hitler announced the introduction of conscription, which aimed to significantly expand the size of the German army. This decision was part of Hitler's broader strategy to rebuild Germany's military strength in defiance of the Treaty of Versailles, which had imposed strict limitations on the size of the German armed forces after World War I.

The introduction of conscription not only allowed Germany to rapidly increase its military personnel but also marked a shift in German military policy towards a more aggressive stance in Europe. This move came alongside the formal announcement of rearmament, setting the stage for Germany's future military expansions and aggressive actions leading up to World War II.

In contrast, the wrong options delve into decisions that did not take place during this time. The reduction of troop numbers in the army contradicts the militaristic ambitions of the Nazi regime. The withdrawal from the League of Nations occurred later as a continued assertion of Germany's sovereignty but was not a specific military decision from this time. The establishment of a navy convention with France did not occur in March 1935; instead, Germany sought to challenge naval restrictions through its own rearmament efforts.