Introductory battle, Dura Europos, as suggested by Mustafa.

Using 6mm figures, Heroics and Ros or Irregular, on 60×30 mm2 bases:

• heavy infantry: 36 figures per base in three ranks / six Irregular infantry bases in two ranks
• medium infantry: 15-18 figures per base / four Irregular infantry bases in two ranks
• light cavalry: 8-10 figures per base / two Irregular (cut to distribute irregularly) bases
• heavy cavalry: 16-18 figures per base / four Irregular cavalry bases in two ranks
• cataphracts: 20 figures per base / four Irregular bases in two ranks
• light infantry: 8 figures per base / two Irregular bases distributed irregularly.

Dura Europos

The Roman Army (14 units)

• 3 Archers/Slingers (light infantry)
• 3 Veteran Cohorts
• 3 Experienced Cohorts
• 3 Light Cavalry
• 2 Armored C (Heavy cavalry)

The Persian Army (17 units)

• 4 Tribal Cavalry (light cavalry)
• 3 Cataphracts
• 6 Paighans (spearmen)
• 4 Wamandaran (archers medium infantry, they may be used as skirmishers for Armati)