We can say Lincoln broke no laws because: Congress eventually approved everything he did.
But more to my point: unlike Jefferson Davis, Lincoln broke no laws for the purpose of destroying the US Constitution.
Instead, all of Lincoln's efforts were to save the Union and its Constitution.
BJK: “Union never formally declared war.”
JCBreckenridge: "What do we call invasions conducted without a formal declaration of war?"
In all of history, formal declarations of war have only been used between nation-states, never to defeat rebellions.
That's why the Confederacy declared war on the United States -- because it wanted to show that it too was a nation-state.
The Union did not declare war because it considered the Confederacy a rebellion.
“Congress eventually approved everything he did”
That’s a bullshit definition. Doesn’t matter what congress approves or not - he suspended Habeaus Corpus - he declared war on a loyal state of the union. If Obama were to do what Lincoln did, you’d be crying tyranny. Which is what it was.
“The Union did not declare war because it considered the Confederacy a rebellion.”
Doesn’t matter what the Union ‘believes’. Lincoln invaded. Virginia defended their own sovereignty.