1929:

The Canadian schooner I’m Alone was taken under fire and captured by CGC Wolcott for violating the Volstead Act.  This precipitates an incident that was adjudicated by an international tribunal.

1941:

Sabotage discovered on Italian vessel at Wilmington, NC.  Coast Guard investigated all Italian and German vessels in American ports and took 28 Italian (27 damaged), 2 German (1 damaged) and 35 undamaged Danish vessels into protective custody, 850 Italian and 63 German officers and crew were imprisoned.  Two months later these vessels were requisitioned by order of Congress for the Latin American trade.