Historically even after the British, French and others declared war on Germany, the German u-boat commanders were ordered to observe the Prize Regulations meaning they could (in theory) sink ships without warning and without placing the ships' crew in safety only if the vessel was
1. armed or
2. observed to carry military equipment or
3. being escorted by a military vessel (e.g. in a convoy with escorts)
This order was in effect until early December, 1939.
So I guess you have just violated the Prize Regulations, disobeyed a direct order from OdK and also attacked a neutral vessel. Good luck at your court marshaling!
