What do you wanna ask tho?
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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On August 25, 1916, President Woodrow Wilson signed the act creating the National Park Service, a new federal bureau in the Department of the Interior responsible for protecting the 35 national parks and monuments then managed by the department and those yet to be established.
Airplanes were vital for ww1 to ease transport of amo and soon guns on the planes including bombs this made it easier for to launch quick air strikes on places like bases vulnerable to air strikes