Hitler soon had cause to regret his decision regarding the fate of Carpatho-Ukraine. In six months, during his 1939 invasion of Poland, the common Hungarian-Polish border would become of major importance when Horthy's government, on the ground of long-time friendship between Poles and Hungarians, declined, as a matter of Hungarian honour, Hitler's request to transit German forces across Carpathian Rus' into southeastern Poland to speed Poland's conquest. That, in turn, allowed the Polish government and tens of thousands of Polish military personnel to escape into neighbouring Hungary and Romania and from there to France and French-mandated Syria to carry on operations as the third-strongest Allied belligerent, after Britain and France. Also, for a time, Polish and British intelligence agents and couriers, including the notable Krystyna Skarbek, used Hungary's Carpathian Ruthenia as a route across the Carpathian Mountains to and from Poland.