There are ways that an employer can change your contract without your consent. They can negotiate changes with a trade union, they can consult with employees and give appropriate notice to change terms and conditions. Your first question is very general.
The second question is more specific. If you have been offered a bonus via email, and you accepted it, then it should be paid. If there is a change in general terms and conditions that there will be no bonuses in future and this has been done with notice and/or via the trade unions then this could be seen as reasonable if there is a downturn in business etc. If it is just you that this affects then a good employer would stand by the offer of a bonus made via email, or give appropriate notice to withdraw the bonus.
A contract cannot be changed without the consent of both parties.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.