The "militia" our forefathers write about is a completely different group than the National Guard (For one thing the National Guard came to being after the Spanish American War. That is a long time before the writing of the the Constitution and the Bill of Rights.).

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U.S. militia. The militia is authorized by the Constitution of the United States, which also defines the militia's functions and the federal and state role. Article 1, Section 8 provides that Congress shall have the power to call forth “the Militia to execute the Laws of the Union, suppress insurrections and repel invasions.” Congress was entrusted with organizing, arming, and disciplining the militia, but the appointment of officers and the training of the militia were reserved to the states. Further provisions were made in the Second Amendment. In peacetime the National Guard is placed under state jurisdiction and can be used by governors to quell local disturbances, as in Newark and Detroit riots in 1967, and to help in times of local disasters, such as floods and hurricanes. In times of war or other emergencies the National Guard is absorbed into the active service of the United States and the president is commander in chief. The National Guard has been partially mobilized during the Korean War, the Berlin crisis of 1961, and the Persian Gulf War and for peacekeeping in Bosnia and Herzegovina. The National Guard's equipment and personnel are standardized to conform with U.S. army regulations. Enlistment is voluntary; compensation, paid by the federal government, is given for periods of drill and field training. The Air National Guard was formed in 1947.

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...After the American Revolution, the First Congress of the United States did not consider the formation of a militia a top priority, and it disbanded the Continental Army. Congress did not officially debate the notion of a militia until the Constitutional Convention in 1787. The Constitution authorized a standing army in its Army Clause (art. I, § 8, cl. 12) and provided for a militia under the Militia Clauses (U.S. Const. art. I, § 8, cls. 15-16). Under the Constitution, the militia is to be available for federal service for three distinct purposes: "to execute the Laws of the Union, suppress Insurrections and repel Invasions." Congress is to organize and discipline the militia, and the states are to appoint officers and train the soldiers.

The National Guard, whose main responsibility since its inception had been the protection of colonial settlements, faced its first significant challenge when it tried to defend the settlements from Native American domination. In 1789, the federal government formed a War Department of approximately seven hundred men for the purpose of defending U.S. soil and its settlements from Native American attack. These small armies failed, and Congress responded to the failure of its small armies to fight off Native Americans in the West by enacting the Militia Act of 1792 (May 8, 1792, ch. 33, I Stat. 271 [repealed 1903]); this act was the militia's only permanent organizing legislation for more than one hundred years. While the act governed the militia, the United States endured three wars—the War of 1812, the Civil War, and the Spanish-American War—and the militia was ineffective in all three. Congress replaced the act with the Dick Act of 1903 (32 Stat. 775) to transform "a frontier police force into a respected and modern fighting machine."

The Dick Act provided for an organized militia—to be named the National Guard—that would conform to the organization of the Army, be equipped through federal funds, and be trained by Army instructors. The act consisted of twenty-six sections and set forth new provisions that had previously only applied to the Army, but now also applied to the newly formed National Guard, including a nine-month limit for reservists' service on active duty, a provision that when on active duty, the reservists would be guided by Army rules and regulations and would receive the same pay as that given to Army soldiers, and a new requirement for the performance of twenty-four drills per year and a five-day summer camp. The act also gave states' governors certain powers over their Guard units, such as the power to excuse their troops from any of the drills or summer camp.