How we cite our quotes: (Act.Scene.Line)
Quote #1
WARWICK
You forget
That we are those which chased you from the field
And slew your fathers, and with colors spread,
Marched through the city to the palace gates. (1.1.92-95)
Warwick tells Henry and company that they've already lost to York and his army, and they'd better watch their backs. Here, "colors" means the battle flags that Henry's army was carrying... and had to run away with after York's army chased them off the battlefield. Warwick is basically saying, "Hey, there's no point fighting anymore, but we can keep going if you want York to beat you again."
Quote #2
KING HENRY
No. First shall war unpeople this my realm;
Ay, and their colors, often borne in France,
And now in England to our heart's great sorrow,
Shall be my winding-sheet. (1.1.130-133)
At the beginning, Henry thinks this war will be his "winding-sheet," which is another word for a burial shroud. If this isn't foreshadowing, we don't know what is. Henry can already see that the war will bring about his end, in one way or another. There's also something scary about the image of war "unpeopling" Henry's land. What's the point of even having a kingdom if everyone who lives there has been killed off in a war?
Quote #3
RICHARD
Therefore, to arms! And, father, do but think
How sweet a thing it is to wear a crown,
[…]
I cannot rest
Until the white rose that I wear by dyed
Even in the lukewarm blood of Henry's heart. (1.2.28-29, 32-24)
When Richard is trying to convince York to fight Henry, he uses this description of war. It's poetic, it's symbolic, and it's downright gross. But hey, it does get across the fact that Richard is out for blood if someone stands between his dad and the crown. He's always willing to fight for his crown—er, his family's crown—er, actually, with Richard, it's never totally clear. For more on the white rose, head on over to "Symbolism, Imagery, Allegory."