Which preposition to use with transshipment

at Occurrences 1%

" Under this there was clearly no authority for discriminating in favor of American goods, either coming direct from a United States Port or by transshipment at Hongkong.

of Occurrences 1%

This cancellation of the agent's credentials, it was alleged, was deemed necessary on account of irregularities with reference to the transshipment of contraband of war from Lorenzo Marques to the Transvaal.

through Occurrences 1%

The United States held that "the destination of the vessel being only such [British] ports ... the port authorities may presumably, and are assumed to be bound to, prevent transshipment through British territory of contraband destined for the Boers.

Which preposition to use with  transshipment