Between the late sixth and mid-ninth centuries the lengthy process unfolded that brought substantial unity to the liturgical-musical practice of the Western Church. The Roman-Benedictine liturgy of Gregory the Great was taken to England in 596–7 by the Italianborn Augustine, prior of the Monastery of St Andrew on the Caelian hill. His purpose was to substitute Roman observance for entrenched Anglo-Saxon, Celtic and Gallican rites as well as pagan customs. Yet when Augustine questioned Gregory about the variety of Christian usages he found, the pope was unwilling to offend local sensibilities and impede the Anglo-Saxons' conversion. Augustine was told to leave in place whatever of the local rites seemed desirable. During the seventh and early eighth centuries an accelerating missionary activity spread the Roman liturgy through France, Germany and northern Italy. Yet wherever it arrived it became similarly intermixed with local material, and it was not until the mid-eighth century that vigorous measures were taken to impose a purer Roman usage. The change came about not through ecclesiastical initiative but through the practical politics of a pious Frankish monarch. Pepin the Short (714–68) sought to increase unity throughout his domain by imposing the Roman rite. He asked Stephen iii (752–7) for clerics to teach the musical rite, and Stephen's successor Paul i (757–67) sent Roman chant books, an ‘antiphonale et responsale’, presumably without notation.