In June, the Hungarian Red Army invaded the eastern part of the so-called Upper Hungary, now claimed by the newly forming Czechoslovak state. The Hungarian Red Army achieved some military success early on: under the leadership of Colonel Aurél Stromfeld, it ousted Czechoslovak troops from the north and planned to march against the Romanian Army in the east. Kun ordered the preparation of an offensive against Czechoslovakia, which would increase his domestic support by making good on his promise to restore Hungary's borders. The Hungarian Red Army recruited men between 19–25 years of age. Industrial workers from Budapest volunteered. Many former Austro-Hungarian officers re-enlisted for patriotic reasons. The Hungarian Red Army moved its 1st and 5th artillery divisions—40 battalions—to Upper Hungary.