Within a year of the election, most opponents of the Nazis had either fled Germany or been taken to concentration camps run by the SS. Other political parties had been banned, but Hitler was not fully secure. Leading officers of the army were particularly suspicious of Hitler's SA and its leader Ernst Röhm. Hitler was also suspicious of Röhm - his control over 4 million SA men meant he was a potential rival. Therefore, Hitler acted ruthlessly to this threat.

29-30 June - squads of the SS broke into the homes of Röhm and other SA leaders and arrested them
Hitler accused Röhm of plotting to overthrow him
Röhm and around 400 others were executed that weekend
This purge became known as the Night of the Long Knives
Hindenburg thanked Hitler for his initiative here
The SA from here remained as a Nazi paramilitary organisation

The Army Oath:

Soon after the Night of the Long Knives, Hindenburg died and Hitler took over as supreme leader (Führer) of Germany. On 2 August, 1934, the entire German army swore an oath of personal loyalty to Hitler.

Hitler Consolidates Nazi Power