Green’s Dictionary of Slang

swamped adj.

(US) drunk.

1860		Spirit of Democracy (Woodsfield, OH) 25 July 4/1: Synonyms [for drunk] [...] slewed, fuzzled, [...] swamped, raddled, nappy, [...] having a brick in one’s hat, limber, tired [...] toddled, slung-shot.
1941		‘Soldiers’ Talk’ in Tampa Trib. (FL) 21 July 5/5: swamped, intoxicated.