The elected members of the Maryland legislature supported the Confederacy. On the other hand, the people did not want to break the Union. In the election of 1860, the Democratic Party split three ways on the Presidency (Bell, Breckenridge, and Douglas). If they had not, Lincoln might not have won and the Southern states would not have seceded.
Lincoln would have won the electoral vote even if all the votes for his 3 opponents had been cast for just one opponent, because he carried enough Northern states for a majority of the electoral college. (Fremont nearly won the election of 1856 when the Republican Party was brand new.) Lincoln got very few votes in the South—in most of the Southern states he was not on the ballot in 1860.
I can see the January 6 Insurrection Committee taking a look at Lincoln jailing the entire Maryland legislature without trial and thinking “what a great idea!”
Commadante Liz Cheney will lead the arresting officers putting the cuffs on every Trump official, explaining to the lapdog press corps that Lincoln did it, therefore it is legal.