Answer: The constitutions guarantee that the government must ask fairly in accord with established rules. It may not act unfairly arbitrarily or unreasonably. The due process limit is placed on the federal government in the fifth amendment and on state and local government's in the 14th amendment: government cannot deprive any person of life liberty or property without due process of the law.
Due process is the legal concept that all citizens will be treated equally in terms of the law. This can be seen in the US Constitution with the 5th and 14th amendments. Here is an example: If a person is arrested for committing a crime, they must have their rights read to them. Once this person is arrested and read their rights, they are entitled to a trail with a jury of their peers present. The aforementioned rights are ones that ALL citizens are entitled to, no matter who you are.
Advantage: They were fighting on their home country. (they didn't have to travel overseas) Britain was fighting France at the same time as they were fighting the US
Disadvantage: They didn't have a trained army. They didn't have much $.
The politician who introduced this term and used it widely was Winston Churchill, one of Britain's most famous prime ministers and a Nobel prize winner for his analysis of history.