World War 1 was known as the deadliest and most brutal war of all time up to that point. War, along with most other things at that time, was modernizing. Nations didn't line up in parallel lines with brightly colored uniforms and shoot at each other on their leader's command anymore, and were instead turning more towards modern warfare where uniforms were being made so it hides the wearer, automatic and more powerful weapons were being made, and soldiers were still somewhat following the lines, but instead in dreadful trenches where a lucky enemy could take you out in a second if your head popped up over the trench. With the beginning of the Great War, man started to realize how bad war could be.
World War 1's "record" for the deadliest war was set to an end by its predecessor, the second world war, and later wars like the Vietnam War would split countries in half like we've never seen before and bring with it great distrust of the government. And not even 40 years later, the biggest and most powerful weapon was created that has the capability to completely wipe out entire cities in a second and cause lasting effects for decades to come. All of these huge leaps and atrocities were birthed from no other than the Great War.
After the first world war, many countries had an economical boom, but for the losers and the nations on the front lines, it was the complete opposite. Germany was hit the hardest after all of the limitations that were put on them from the Treaty of Versailles, which put a limit on their military, land like the Rhineland was demilitarized, the loss of over 13% of Germany's prewar territories, Germany having to pay 132 billion gold marks ($33 billion USD), and much more. All in all, this put Germany into a depression. While the other nations were caught up in domestic business with either the depression or their economic booms (depending on what decade it was), an art school reject and politician, known as Adolf Hitler, was promising and saving Germany from their hard times. When people are desperate, they are more willing to do almost anything to escape those difficult times. As we know, after becoming chancellor of Germany in 1933, Hitler then started his plan to take over Europe, then the world.
Skipping forward to 1941, Japan attacked the US at Pear Harbor which caused congress to declare war just a few days later. The United States of America is now out of "isolationism". After the end of the second world war, the US started its way to become the world police we all know today. The US then became involved in the Cold War which had smaller conflicts/wars which involved the Korean and Vietnam War, and other smaller conflicts like Bay of Pigs invasion and the Berlin Wall. After the Cold War was put to an end, the US got involved in Middle Eastern affairs like with the Gulf Wars and the war on terrorism which is still happening today. America wasn't the only nation affected by the first world war, all countries like Russia, France, and the UK were all and still are affected by it to this day.
Russia had to withdraw from the war due to the communists and Vladimir Lenin taking control of the country, which, in turn, helped create their involvement in the Cold War and the fall of communism in the Russia which many are still affected by it and it contributes to some poorer parts of Russia's economy. France, being on the front lines, was destroyed and had a hard time recovering from it. France also built the Maginot Line just in case Germany invades again, which they did, and the failure to think about Germany going around and over it was their ultimate demise. The UK and other imperialist nations gave up a lot of their pre-ww2 territories which caused inner conflicts of themselves.
All in all, the Great War directly led to WW2, which led to later wars that are still occurring today. Thank you all for taking the time to read this, and feel free to comment your opinions and we'll have a discussion on them. Thanks again and have a wonderful day!
Source: reddit post