व्यामिश्रो वा हस्तिरथाश्वानां चक्रान्तेषु हस्तिनः पार्श्वयोरश्वा रथा उरस्ये ॥ कZ_१०.५.३१ ॥
vyāmiśro vā hastirathāśvānāṃ cakrānteṣu hastinaḥ pārśvayor aśvā rathā urasye
Or (the array may be) mixed: at the wheel-ends/periphery are elephants; on the flanks are cavalry; at the front/center (breast) are chariots.
To use elephants as a shock-and-anchor element on exposed extremities, stabilizing the perimeter against breakthroughs.
Flanks demand speed for counter-moves, pursuit, and screening—roles suited to cavalry.