Complex sentence: Major Mushegh Malkhasyan's 789th Regiment was the first hit by the German tank attack, but the regiment was able to separate the German tanks from their infantry and break up the counterattack.
Split into simpler sentences: Major Mushegh Malkhasyan's 789th Regiment was the first hit by the German tank attack. The 789th was able to separate the German tanks from their infantry and break up the counterattack.