From the BBC website:

Composition involved, in Gaelic parts, the commutation of the chief's right to take up supplies for his household and quarter his kerne and galloglass on his subjects for defence. This practice, known as coign and livery, had also spread to outlying English parts. Its English equivalent, purveyance for the army and governor's household, was also commuted, so reducing the queen's overall charges but generating fierce resentment in the Pale where it was seen as a new, unconstitutional, system of military taxation, levied without the subject's consent.

In short- The poor were made to pay the wages of the occupying army- refusal meant legal expropriation.

The use of Olde English terms is a classic method informing while at the same time evading the truth.

Democracy- don't you love it!