General Motors recognized the United Automobile Workers Union.
While both Greek and Romans were pretty ethnocentric by modern standards, the Romans assimilated far more people into their institutional lives.
Many non-Greeks adopted Gteek lifestyles, language and habits after the age of Alexander, but the cross-pollination was more frequently cultural than political. Cleopatra might have dressed like an Egyptian queen and patronized the Egyptian gods, but she wouldn't have had Egyptian generals or Egyptian judges. The Greeks tended to settle into the cultures they occupied like the British in India: remaining separate from and believing themselves superior to the people around them, even while encouraging the 'natives' to adopt their culture habits.
Romans did a much more thorough job assimilating the peoples they conquered. Non-Romans could and did become citizens, even from very early times. This started with neighboring groups like the Latins, but eventually extend to the rest of Italy and later to the whole empire. Eventually there would be "Roman" emperors of Syrian, British, Spanish, Gallic, Balkan, and North African descent Farther down the social scale the mixing was much more complete (enough to irritate many Roman traditionalists). This wasn’t just a practical accommodation, either — when emperor Claudius allowed Gauls into the Roman Senate he pointed out that by his time the Romans had been assimilating former enemies since the days of Aeneas.
I think it's just the right thing to do.
The most surprising thing for me personally was the set up of the trenches, there is a very good system where the front line is the first to attack or be attacked while the others are there as backups. If someone were to get hurt within the first trench, there are easily accessible routes for the soldiers to take to retreat to safety, on the contrary, if the front lines were in need of any reinforcement whatsoever, there is a clear way to travel for the soldiers to get more ammunition or man power.
Most civilizations have practiced some form of slavery in their development. Famine or fear of stronger enemies might force one tribe to ask another to help and give themselves in a type of bondage in exchange that was similar to the European serf system.
Arabs also had slave trading, they exchanged slaves for goods from other parts of the world.
Until that moment, slavery was not linked to color, it was mostly linked to war and economic opportunities.
Slavery became a matter of color when Portugal started to explore the West Coast of Africa in 1444. Because African slaves were identified by their skin color since then, slavery became a matter of color and not economic opportunities or war. Europeans settled in Brazil, Caribbean, and North America and developed a system of racially based slavery.