Arthashastra
द्वे शते धनुषां गत्वा राजा तिष्ठेत् प्रतिग्रहे । भिन्न संघातनं तस्मान् न युध्येत अप्रतिग्रहः॥
Having gone to a distance of 200 bows, the king should take his position together with the reserve of his army; and without a reserve, he should never attempt to fight, for it is by the reserved force that dispersed troops are collected together.
english translation
dve zate dhanuSAM gatvA rAjA tiSThet pratigrahe । bhinna saMghAtanaM tasmAn na yudhyeta apratigrahaH॥
hk transliteration by Sanscript