at the Battle of Lexington, in the early morning of April 19, 1775.
The 'battle" was actually a skirmish when British soldiers enroute to Concord came across armed colonial militiamen. After a brief exchange of fire, the Americans dispersed. It was not until later in the day that Minutemen, warned by Revere, Dawes, and others, routed a force of Redcoats at the Battle of Concord. These separate battles are often considered as a whole as the first open conflict in the war
the signing of the Treaty of Versailles
The Treaty of Versailles ending fighting between the Central Powers and the Triple Alliance (minus Russia).
The Treaty of Versailles set up a series of restrictions on the Central Powers following World War I. Germany was most restricted under the treaty due to the War Guilt clause. The Treaty also set up the League of Nations which would monitor and negotiate in the case of invasion in the future.
I think it would be the Executive only because the people are more aware to what the president will say and how they run this country. Take our newest president, Mr. Donald J. Trump, he is our president and now a lot of people are more aware of what he is doing to our nation and how the people react can be beyond his doing depending what new laws or bills he passes or sets. Riots could start, or people could praise him. SNL had done skits since he's been in office that were about him, that counts as responding, though in a comedic form it still counts to what they have responded to.
Disagreement and resentments is the answer :)