Mith frethe to wasane ‘to be in peace’: Remnants of the instrumental case in thirteenth and fourteenth century Old Frisian

The case system in Old Frisian is commonly described as including four cases: nom., gen., dat., acc. Only a few lexical or onomastic relics are said to attest to the former existence of an instrumental and a locative case. Closer scrutiny, however, shows that a morphologically distinct instrumental and locative case were fairly consistently applied in some declensional classes, at least in some dialects of Old Frisian (c. 1250-1400). Traces are in particular found in texts from the Ems Frisian region, but are also attested in Codex Unia, reflecting Old West Frisian. The instrumental ending was PFri *-u < PIE *-oh1 throughout (nearly) all declensional classes, a uniformity typical for a case with a low frequency. The origin of the PFri locative ending *-i, restricted to the masculine a-stems, remains unclear. The reconstructed distribution of case endings found for the earliest stages of Old Frisian largely parallels the situation in nineteenth century Old Saxon.