From Dynomight:
In September 1893, Churchill was admitted, on his third attempt, to the Sandhurst military college. He wrote to his father, “I was so glad to be able to send you the good news on Thursday.” His father, a former Chancellor of the Exchequer and leader of the House of Commons, wrote back a week later. The full text the reply doesn’t seem to be available, but we have these glimpses:
You should be ashamed of your slovenly, happy-go-lucky, harum, scarum style of work. […] Never have I received a really good report of your conduct from any headmaster or tutor. […] Always behind, incessant complaints of a total want of application to your work. […] You have failed to get into the 60th Rifles, the finest regiment in the army. […] You have imposed on me an extra charge of some 200 pounds a year.
[…]
Do not think that I am going to take the trouble of writing you long letters after every failure you commit and undergo. […] I no longer attach the slightest weight to anything you may say. […] If you cannot prevent yourself from leading the idle, useless, unprofitable life you have had during your school days, […] you will become a mere social wastrel, one of the hundreds of public school failures, and you will degenerate into a shabby, unhappy and futile existence. […] You will have to bear all the blame for such misfortunes.
[…]
Your mother sends her love.
Churchill was 19.
....MUCH MORE
