Complex sentence: A common Austro-Hungarian War Ministry was formed immediately for the large Common Army, but it had no right to command directly the smaller Landwehr and the Honvéd armies, which were respectively placed under the direct control of the separate Austrian and Hungarian Ministries of Defence.
Split into simpler sentences: A common Austro-Hungarian War Ministry was formed immediately for the large Common Army, but it had no right to command directly the small Landwehr and the Honvéd armies. The Landwehr and the Honvéd armies were respectively placed under the direct control of the separate Austrian and Hungarian Ministries of Defence.