Anybody can help me?
There, on September 17, 1862, as many as 100,000 Yankee northerners and Rebel southerners, fighting a great civil war, collided on pastureland next to a tiny stream called Antietam Creek in an epic 12-hour battle.
(What does Yankee and Rebel means in here?)

Confederate General Robert E. Lee had won victory after victory - but on his own soil in Virginia. He needed a triumph in northern territory that would persuade France and England to endorse the breakaway Confederacy and provide it with arms to win the war.
(What is won victory after victory and what is breakaway Confederacy)

In those fields today, you can almost feel and hear the fierce battle that decided it all, especially when you walk down a sunken lane that the locals called “Hog Trough Road” because pigs had worn a depression in the earth going to and from a barn.
(what does worn and depression means in here??)

anybody want to help me / thank!^^

Question

Anybody can help me?
There, on September 17, 1862, as many as 100,000 Yankee northerners and Rebel southerners, fighting a great civil war, collided on pastureland next to a tiny stream called Antietam Creek in an epic 12-hour battle.
(What does Yankee and Rebel means in here?)

Confederate General Robert E. Lee had won victory after victory - but on his own soil in Virginia.  He needed a triumph in northern territory that would persuade France and England to endorse the breakaway Confederacy and provide it with arms to win the war.
(What is won victory after victory   and  what is breakaway Confederacy)

In those fields today, you can almost feel and hear the fierce battle that decided it all, especially when you walk down a sunken lane that the locals called “Hog Trough Road” because pigs had worn a depression in the earth going to and from a barn.
(what does worn  and depression means in here??)

anybody want to help me /  thank!^^

Answer

"What does Yankee and Rebel means in here?"
Yankees are Northerners, who fought for the Union during the American Civil War;  and Rebels are Southerners, who fought for the Confederacy. "Yankee" is still occasionally used in a tongue-in-cheek sense to talk about people from the northern United States. Also, people outside of the United States sometimes refer to Americans as "Yanks" or "Yankees."

"What is won victory after victory and what is breakaway Confederacy"
"Won victory after victory - but on his own soil in Virginia" - it means that Robert E. Lee won many battles in his home state of Virginia, but in order to persuade France and England to support the Confederacy, he needed a victory outside of Virginia.

"Breakaway" - made up of two words, "break" and "away" - during the Civil War, the Confederate states "broke away", i.e. separated, from the rest of the country.

"What does worn and depression mean in here??"
"worn a depression" - it means that the pigs' hooves made marks in the ground.