THIS PAPER TRACES the origin and early history of the three digraphs <th>, <ch> and <uu> in early Old English and in some of the Continental Germanic languages. Today, the digraphs form part of the graphemic systems of various European languages. Their creation and application in the Early Middle Ages hence represents an important graphemic innovation, which has permanently solved some of the problems arising in the process of creating orthographic systems for the vernacular languages with the Latin alphabet – despite the fact that the transmission of the digraphs from the Early Middle Ages to the Modern Era did not proceed in a straightforward line. By way of an introduction, I will briefly describe the distribution and use of the three digraphs in the orthographies of modern European languages, which, to some extent, still reflect the areas in which the digraphs were used in the Early Middle Ages. I will then provide a detailed account of their use in Old English of the eighth century. It has been suggested that Irish influence is responsible for the use of <th> for a dental fricative and of <ch> for a palatal/velar fricative in Old English. While Irish influence should certainly not be underestimated, there is stronger evidence, as I argue, for attributing the origin of the digraphs to the Merovingian Franks or, more precisely, to the spellings used for Frankish names in Latin charters. The Merovingian hypothesis is strengthened by the fact that the same graphs were also adopted into Old High German writing. The adoption of the digraphs, however, should not be envisaged as a process of straightforward borrowing, but rather as an independent reinterpretation and extension based on a perception of the graphs as essentially Latin spellings. Thus, the paper highlights the complex relationship of the spelling systems of the early medieval vernaculars and Latin, the ‘father tongue’ of the Middle Ages. On a theoretical level, it yields some insights into the general mechanisms of graphemic change in non-standardised scriptae.