Read the following excerpt. It is from the first speech that Winston Churchill gave to the House of Commons upon accepting the role of Prime Minister in 1940. Months earlier, England had declared war on Nazi Germany. I would say to the House, as I said to those who have joined this government: "I have nothing to offer but blood, toil, tears, and sweat."
We have before us an ordeal of the most grievous kind. We have before us many, many long months of struggle and of suffering. You ask, what is our policy? I can say: It is to wage war, by sea, land and air, with all our might and with all the strength that God can give us; to wage war against a monstrous tyranny, never surpassed in the dark, lamentable catalogue of human crime. That is our policy. You ask, what is our aim? I can answer in one word: It is victory, victory at all costs, victory in spite of all terror, victory, however long and hard the road may be; for without victory, there is no survival.

From Winston Churchill, "Blood, Toil, Tears, and Sweat"
Based on the excerpt, what is the purpose of Winston Churchill's speech?