An Etymological Dictionary of the German Language/Heer
Heer, n., from the equiv. MidHG. hęre, OHG. hęri, hari, n., ‘army’; comp. Goth. harjis, m., AS. hęre, m., OIc. herr, m.; a common Teut. word for ‘army,’ still current in Swed. and Dan. här, Du. heer- in compounds. AS. hęre was supplanted in the MidE. period by the Rom. army; yet AS. hęre-gcatwe, ‘military equipment or trappings,’ has been retained down to ModE. as heriot; similarly the AS. word for har-bour (comp. Herberge). The term chario-, ‘army,’ met with in Teut. proper names of the Roman period, corresponds to OIr. cuire, ‘troop,’ OPruss. karjis, ‘army,’ of which Lith. káras, ‘war,’ is the base (Heer, lit. ‘that which belongs to war’); to this OPers. kâra, ‘army,’ is allied?. In MidHG. and earlier ModHG. there is another deriv. of the root kar, viz. harst, MidHG. also harsch, ‘body of troops.’ The verbal form from the assumed word for ‘war' was perhaps Goth. *harjón, ‘to wage war upon’; comp. OIc. herja, ‘to go on a predatory expedition,’ AS. hęrigan. E. to hurry, to harrow, OHG. heriôn, MidHG. hern, ‘to ravage, plunder.’ Comp. further Herberge and Häring.