Then what happened when all the men who volunteered at the first of the war thinking that they were fighting and dieing to "Preserve the Union" found out they were fight to "free the slaves"?
In advertising that is called the "Bait and Switch".
Advertise one thing at a low cost then when you get into the store the saleman tells you he hasn't got that item anymore and trys to sell you something else more expensive.
It is very unethical and in some states illegal.