SELECT "Nationality" FROM table_48278 WHERE "Fate" = 'sunk (mine)' AND "Tonnage (GRT)" < '2,266'
Which Nationality has a Fate of sunk (mine), and a Tonnage (GRT) smaller than 2,266?
CREATE TABLE table_48278 (
    "Date" text,
    "U-boat" text,
    "Name" text,
    "Nationality" text,
    "Tonnage (GRT)" real,
    "Fate" text
)