This is most likely specifically asking for World War I.
The first thing is rather not a gain, but a trust. Most of Europe, Asia, as well as the Middle East and Africa, were split into two camps. These camps were alliances, known as the Central Alliance (the German & Austrio-Hungary camp), and the Allies (The British & French camp).
The war was triggered by the assassination of Archduke Franz Ferdinand and his wife Sophie by a Serbian Nationalist who wanted to see a free Serbia. While Serbia was open to paying for reparation, Austrio-Hungary threw away the table in hopes of conquering and claiming Serbia for their own. The failure for the gears of war to stop before then was what caused the countries to go at war. Each country was bound by their alliance contract to help their members at need, and so it set off a chain reaction that ensued into a global war.
They had nothing to gain, but to keep their own honor, the survivability of their state, and the trust of their allies.
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D John Locke’s Two Treatises of Civil Government inspired the principle of natural rights, which colonists used to substantiate their belief that the British government was tyrannous.
In the Declaration of Independence, Jefferson identified three natural rights "Life, Liberty, and the Pursuit of Happiness." Which were influenced by the writings of John Locke
It establishes the court system
It stated that the judicial power of the United States shall be vested in one Supreme Court and in such inferior courts such as the congress may from time to time ordained and establish
