How we cite our quotes:
Look back into your mighty ancestors:
Go, my dread lord, to your great-grandsire's tomb,
From whom you claim; invoke his warlike spirit,
And your great-uncle's, Edward the Black Prince,
Who on the French ground play'd a tragedy,
Making defeat on the full power of France,
Whiles his most mighty father on a hill
Stood smiling to behold his lion's whelp
Forage in blood of French nobility.
O noble English. that could entertain
With half their forces the full Pride of France
And let another half stand laughing by,
All out of work and cold for action! (1.2.3)
When Canterbury and Ely urge Henry to channel his ancestors and "forage in blood of the French nobility," it's pretty clear that they think it's Henry's patriotic duty to declare war on France.
She hath been then more fear'd than harm'd, my liege;
For hear her but exampled by herself:
When all her chivalry hath been in France
And she a mourning widow of her nobles,
She hath herself not only well defended
But taken and impounded as a stray
The King of Scots; whom she did send to France,
To fill King Edward's fame with prisoner kings
And make her chronicle as rich with praise
As is the ooze and bottom of the sea
With sunken wreck and sunless treasuries. (1.2.6)
Henry worries that invading France will leave England's borders vulnerable to attack from outsiders. After all, when Henry's great-grandfather led a campaign on foreign soil, England was invaded by their neighbors, the Scottish. Canterbury's response is that England was hardly threatened by the Scots. In fact, she took the Scottish king prisoner, which was quite a feather in her cap. In other words, Canterbury says that England's been racking up successful military campaigns left and right, making the country rich with the "treasures" of victory.
But this lies all within the will of God,
To whom I do appeal; and in whose name
Tell you the Dauphin I am coming on,
To venge me as I may and to put forth
My rightful hand in a well-hallow'd cause. (1.2.11)
Henry frequently declares that God is on his side. Here, he warns the Dauphin (via the Messenger) that, when he invades France, he's coming as God's avenger.