Ten armored cars were seized by the Slovaks when they declared independence in March 1939, but eight additional OA vz. 30s fell into their hands when Czech troops were sought refuge in Slovakia after fighting the Hungarians in Carpatho-Ukraine. One was destroyed during the Slovak-Hungarian War that began a week later. The seventeen surviving OA vz. 30s formed one company in the Armored Battalion "Martin" formed by the Slovak Army in mid-1939, but that was reduced to a platoon by late 1939. Four armored cars reinforced the 2nd Infantry Division during the invasion of Poland and three others reinforced a cavalry reconnaissance unit in the vicinity of Sanok. A company of six OA vz. 30s was part of Mobile Group Kalinčiak that was formed on 5 September to work with the 2nd Infantry Division, but saw no combat before being withdrawn back to Slovakia on the 21st.