He had nowhere to flee and had no choice but to surrender.
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遁 is a classical/literary character. In modern standard Chinese, 逃跑 or 逃脱 are the everyday equivalents. 遁 appears mainly in idioms (遁形 = to vanish, 遁世 = to withdraw from the world) and literary or historical writing.
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遁 contains 辶 (movement radical) + 盾 (shield). Picture hiding behind a shield and slipping away, fleeing under cover.
辶 is the motion radical 辵 in its bottom-left walking form. It signals stealthy movement, here slipping away, escaping, vanishing into hiding (遁形, 遁走). Sister verbs 逃 (flee), 退 (retreat), 避 (avoid) share the radical and the going-out-of-sight signal.
盾 supplies the sound exactly: same initial, rime, tone. The shield-imagery adds an apt flavour, to flee while hidden behind cover, slipping away under the shadow of a shield. Same phonetic drives 楯 (railing) and 循 (follow along).
