"What law did Trump break?"
Incitement of an insurrection against the U.S. government to name one.
He swore an oath to the Constitution to protect this country. He failed.
The
oath of office of the president of the United States is the
oath or
affirmation that the
president of the United States takes after assuming the presidency but before exercising or carrying out any
presidential powers or duties. The wording of the oath is specified in
Article II, Section One, Clause 8, of the
United States Constitution.
This clause is one of three
oath or affirmation clauses in the Constitution, but it is the only one that actually specifies the words that must be spoken.
Article I, Section 3 requires Senators, when sitting to try impeachments, to be "on Oath or Affirmation."
Article VI, Clause 3, similarly requires the persons specified therein to "be bound by oath or affirmation, to support this Constitution." The presidential oath requires much more than that general oath of allegiance and
fidelity. This clause enjoins the new president to swear or affirm that he "will to the best of my ability, preserve, protect and defend the Constitution of the United States."
[1]
en.wikipedia.org