A more thorough explanation:

Definition: Military necessity is a principle of warfare that allows the use of force to achieve a desired end, as long as the force used is not more than what is required by the situation. This principle is based on the Hague Convention on Laws and Customs of War on Land of October 18, 1907, which prohibits the destruction or seizure of enemy property unless it is absolutely necessary for the war effort.

• During a battle, a military commander orders the destruction of a bridge to prevent enemy troops from crossing it. This action is considered a military necessity because it is necessary to achieve the desired end of preventing the enemy from advancing.
• However, if a commander orders the destruction of a civilian hospital, this would not be considered a military necessity because it is not required to achieve any military objective and would be a violation of international law.

The examples illustrate that military necessity is a principle that allows the use of force to achieve a desired end, but only if it is necessary and proportional to the situation. It is important to distinguish between actions that are necessary for the war effort and those that are not, as the latter can result in war crimes and violations of international law.