John Wilkes Booth is reported as saying "Sic semper tyrannis" when he assassinated Lincoln:-
The Knights of the Golden Circle were established on 4th July 1854 in Lexington, Kentucky, graph below showing Alnilam rising with the Sun.
I thought links below would help:-
By reading both please note that John Wilkes Booth and fellow conspirators had a meeting to plan how to kidnap President Lincoln, this meeting was on
15th March 1865, no doubt he found the symbolism fitted his black humour being the IDES OF MARCH.
He had planned to kidnap President Lincoln in Washington DC on 17th March 1865, but the attempt didn't happen, as Lincoln changed his plans.
April 14th 1865 was Good Friday, so i feel that John Wilkes Booth thought the symbolism with assassination was auspicious, but he had only found out
earlier in the day that Lincoln would be attending Fords Theatre!
Finally this day wasn't aligned to a day marker, but the conspirators had planned simultaneous assassinations of Lincoln, Secretary of State, William
Henry Steward and Vice President Andrew Johnson, all at the mysterious time of 10:15pm, perhaps not so mysterious!
Firstly i will deal with the attempted kidnap of President Lincoln, that didn't happen in Washington DC as the President changed his plans for the
evening of 17th March 1865.
However Booth had chosen midnight day marker for Sirius was setting in the West.
Astronomy graph below showing that midnight day marker was picked for 17th March 1865 in Washington DC, with the failed kidnap attempt, Sirius setting
in the West:-