The dress code for the event is black tie.
Those who identify as gentlemen should ideally wear a black tuxedo, although a dark (preferrably black) suit with a black tie or bowtie would be an acceptable alternative.
Those who identify as ladies should wear a cocktail dresses or evening gowns. Short dresses are discouraged.
If you wear a white (or off-white) a bridesmaid may or may not murder you.
Note: the wedding will be mostly outdoors, and there will be gravel. You might want to wear block heels instead of stilettos.
For inspiration, see the photos below.