Why was clemency trending last week?
1540s, probably from Middle Dutch tromme "drum," common Germanic (cf. German Trommel, Danish tromme, Swedish trumma), probably of imitative origin. Not common before 1570s. Slightly older, and more common at first, was drumslade, apparently from Dutch or Low German trommelslag. Machinery sense attested from 1740, from similarity of shape.
1570s, from drum (n.). To drum (up) business, etc., is American English 1839, from the old way of drawing a crowd.
Ancient slow, cylindrical magnetic media that were once state-of-the-art storage devices. Under BSD Unix the disk partition used for swapping is still called "/dev/drum"; this has led to considerable humour and not a few straight-faced but utterly bogus "explanations" getting foisted on newbies.
See also "The Story of Mel".