Basically, before 1973, the president had more power over the military and had more freedom to command the military as the president wished. This was seen in Vietnam which turned out to be a disaster. It was decided to limit the president's military power, and he would need the consent of congress to whatever operation he planned to do.
summary: limit president's military power
The government has grown to meet the needs of the people
In Marbury, the Supreme Courttook the power to declare that laws passed by Congress were null and void if they (in the Court'sopinion) violated the Constitution. The significance of Marbury v.Madison is that the ruling in thatcase gave the Supreme Court of the United States the power of judicial review.