What's the meaning of the phrase 'Cry havoc and let slip the dogs of war'?
The military order Havoc! was a signal given to the English military forces in the Middle Ages to direct the soldiery (in Shakespeare's parlance 'the dogs of war') to pillage and chaos.
The 'let slip' is an allusion to the slip collars that were used to restrain dogs and were easily 'let slip' to allow the dogs to run and hunt.