I spent hours researching this and I couldn’t find any indication that Lincoln invoked the IA. Believing that the drop was asking about a time in the past that a President invoked the IA, I suggested it might be Jefferson against Aaron Burr, but I stated at the time that it wasn’t conclusive.
What if the drop is referring to President Trump? We’re only now beginning to understand that the drops are fluid when it comes to time. We thought they were referring to the moment in time when the drop was made, but we know now that many referred to a time in the future and to events that hadn’t happened yet. Was this one of them?
I don’t think the Insurrection act is necessary for the drop to be accurate. There are other means to use Mil just as Lincoln did, as in Publius’ comment above. I do favor the IA of course, and very possible Trump did invoke, but may not be required, esp. because of the foreign enemy influence.
We just don’t know.
Q post 28
Plain as day answer