"....tended to compensate those who became unable to provide for themselves due to service related injuries."

This reminds me of the agent orange and Gulf War syndrome disabilities, to which many of those disabilities developed years after getting out of the service. From this and of this kind of injury, the government has been fighting tooth-and-nail not to recognize these as a service related disability. I don't know where they stand today, but I believe agent orange related disabilities have been begrudgingly accepted as military service related disability. Related to this is your next question. The military has a list of every type of disability qualifying for compensation that they recognize. Say if you are on flight duty and trip over a chalk chain on a flight deck and blew your ACL in your knee. Depending on the degree of injury it qualifies that person for disability compensation. Another example is a service member gets into a car accident and his injury results in a permanent loss of use of his right hand. Depending on whether it was ruled service related, it qualifies for disability compensation. If say the service member was driving impaired and the toxicology report finds he was driving over the legal limit of alcohol, that service member does not qualify for disability compensation. That same individual though can qualify for SSA benefits.