history...what has it to teach us if anything?

A dear friend asked me to talk briefly on history, I can only talk from my perspective and that's of a lover of history and what it should teach us.
 A man does what he must - in spite of personal consequences, in spite of obstacles and dangers and pressures - and that is the basis of all human morality.
Winston Churchill
I believe history has the capacity to teach us so many lessons yet sadly over time our world governments have chosen to deliberately ignore those valuable lessons.
Take for example WWII, we all know pretty much everything that happened there, we all swore black and blue it would never happen again, yet have we not all been involved in several wars of late, why is this?
Is it possible to be an adult, a thinking adult and not bow down to pressure and instead of putting on our war paint put on our thinking caps?
We shall defend our island, whatever the cost may be, we shall fight on the beaches, we shall fight on the landing grounds, we shall fight in the fields and in the streets, we shall fight in the hills; we shall never surrender.
Winston Churchill
Winston Churchill was an iconic figure in his time and now, however could he have done things differently, perhaps, would the world have listened to him if he had said let's sit this out and think awhile, sadly no I don't believe so.  Even Winston knew this.  Life is full of perilous challenges, our governments while not perfect by any means truly strive to protect our basic fundimental rights of freedom and protection, peace is a dangerous dream, it's fraught with what if's and hard core extremists.
 Every gun that is made, every warship launched, every rocket fired, signifies in the final sense a theft from those who hunger and are not fed, those who are cold and are not clothed.
Dwight D. Eisenhower
It is up to us as a whole to carry the torch for peace, to live our daily lives peaceful, to promote to our children a world that can co-operate with each other and look after each other, regardless of race, gender, materialistic status or personal beliefs, if we look to our children and our ghostly ancestors past perhaps an answer, an attainable answer can be found.
 Never think that war, no matter how necessary, nor how justified, is not a crime.
Ernest Hemingway