What is "post-haste"

Usage examples of "post-haste".

Major McColloch, who had been warned by Wetzel of the fever of unrest among the Indians--a fever which broke out every spring--had gone to Fort Pitt with the hope of bringing back reinforcements, but, excepting the young soldier, who had volunteered to return with him, no help could he enlist, so he journeyed back post-haste to Fort Henry.

When he had taken his seat on the tribunal and the Capuans who had been brought out were being bound to the stake, a mounted messenger arrived post-haste from Rome and handed Fulvius a despatch from the praetor C.

Charles Wogan, who comes from Rome post-haste with the Pope's procuration for the marriage.