A result of the publication of Rachel Carson’s
Silent Spring was that the modern environmental movement gained
support.
Gavrilo Princip was trying to assassinate Franz Ferdinand, heir to the Austrian throne. He had failed the first time, when suddenly as he was weeping at a restaurant Franz's car ent by him. He then killed him and the Great War (name for WW1 before WW2) happened.
I'm not 100% what the question is, but I'm guessing you are trying to come up with a thesis statement for an essay.
A good thesis statement could be...
The Declaration of Independence is truly one of the most influential U.S documents.
I hope this helps!