In 660, the Tang dynasty and the shinla united to invade the Baekjae. The Tans dynasty's army and shinla's army went to Baekjae. So the greatest general Gyabak. He brought 50.00 thousand soldiers to fight against them. The army of shinla couldn't win the Baekjae easily. However, shinla got the power when the the Hwarang gwanchan died from fighting. SO finally the could win the Baekjae. 
In conclusion, I felt a bit sad because the Baekjae was the most powerful country in that time with Goguryeo just disappeared in the history by other countries at once. ...