It is accepted that the Byzantine Empire fell in 1453 to the Ottomans under Mehmed II finally took over Constantinople after 53 days of battle. However, there were several other successor states to the Byzantine Empire such as the Despotate of Morea and the Empire of Trebizond that could be argued to be "Byzantine". Some didn't even fall until 1479. That being said, the Roman "Byzantine" Empire definitely fell in 1453.
Its france
and it was called the Franco-Ottoman alliance
The four acts that were passed in 1774 were the Boston Port Act, the Quartering Act, the Administration of Justice Act and the Massachusetts Government Act. All four acts were meant to curtail rebellious behavior and to suppress any idea of revolt in the colonies.
The four natural barriers that protected Egypt in each direction would be the sea, rivers, desert, and mountains, although of course now these offer little protection.