Origin & Development:
International Humanitarian Law (IHL) is a branch of International Law. It doesn't not deal with legality of war but only deals with humanity during the war. It is a bundle of rules regarding armed conflict to limit the effects of war or to help the sick or wounded. Certain principles are given which are only applicable after the war has started.

IHL is inspired by considerations of humanity and the mitigation of human suffering. The main source of IHL is Treaty Law and Customary Law of war. In the Indian epic Mahabharat approximately 400 BC, the laws of Manu incorporated provisions outlawing the killing of surrendering adversaries who were no longer capable of fighting. These included people who were aged, soldiers who were injured and lost their hand, leg and any other body part.

In 1859 by Henry Dunant with the help of his written book named The Memory of Solferino the thought of IHL originates. This book is completely based on observations of the battle of Solferino where approximately 40,000 people died and the rest of them were wounded. There was no one to help them that reflected their inhuman nature.

Establishment of IHL:
For the very first time in 1864 in the Geneva Convention it was discussed by the ICRC (International Committee of the Red Cross). ICRC is an organization which serves nursing facilities to provide protection and assistance to the victims or wounded people during the war. It was formed on 18th February, 1863 and mentioned legally under Geneva Convention 1964. It's co-founder is Gustev Monior.

Principles of Geneva Convention;

• Humanity
• Unity
• Impartiality
• Independence
• Universality

After that in 1868 passed a declaration of Saint Less Petersburg; it also talks about lHL.

After that in 1899 a first Hague Peace Conference held under this one martine clause added under the IHL. That is if any country does not sign these laws also applicable to them. The last Hague Peace Conference was held in 1907.

After that in 1949 under the Geneva Convention there are some latest developments added under the IHL such as follows;

• Immeluation of conditions of sick and wounded people in the field
• Immeluation of conditions of sick and wounded peoples in the Sea;
• Protection of prisoners of war;
• Protection of civilians.

One additional protocol was added in 1977 to support the Geneva Convention.

Legal Maxims:
There are two legal maxims which talks about the applicability of IHL such as follows;

Jus- ad-bellum: It deals with the legitimacy of conflict. Which means before the starting of war it is related to the reasons for war and the right of war. Under UN (united nation) Charter Article 2 states about; don't interfere sovernaty of the country without any reasonable grounds and also provide a principle during the war such as follows;

• Legitimate authority can only start the war only by declaration of war. Legitimate authority means the President of the country or the Prime Minister of the country
• Right intention which means war to maintain the peace intentionally;
• Necessity in case if there is no any other option the last necessity is war;
• Just cause which means a strong reason for war;
• Probability of success to win the war on the basis of distinction, proportionality, prisoners, weapons and members.
   

Jus-in-bello: It is related to IHL which deals with situations that arise after war has started. There are certain principles mentioned such as follows;

• Principles of distinguishing between civilians and combatants;
• Principles of proportionality which means balance between both countries weapons and any other forces;
• Prisoners must be treated as a human being without any torture;
• Weapons which are prohibited under international law should not be used;
• Cannot attack ICRC members.

Conclusion:
The only reason to implement the International Humanitarian Law is to prohibit the use of means & methods of warfare that are indiscriminate or that cause superfluous injury or unnecessary suffering is to be avoided and develop the humanity at the International level treat all humans are the same they have the right to life, food and shelter and also the treatment those sick and wounded.