Arak
... that upon hearing of Khalid ibn al-Walid's reputation in battle, the Roman-led Arab Christian garrison of Arak peacefully surrendered their fort to his army?
... that upon hearing of <a href="./Khalid_ibn_al-Walid" id="mwAzc" rel="mw:WikiLink" title="Khalid ibn al-Walid">Khalid ibn al-Walid</a>'s reputation in battle, the <a href="./Byzantine_Empire" id="mwAzg" rel="mw:WikiLink" title="Byzantine Empire">Roman</a>-led <a href="./Arab_Christians" id="mwAzk" rel="mw:WikiLink" title="Arab Christians">Arab Christian</a> garrison of <b id="mwAzo"><a href="./Arak,_Syria" id="mwAzs" rel="mw:WikiLink" title="Arak, Syria">Arak</a></b> peacefully surrendered their fort to his <a href="./Rashidun_army" id="mwAzw" rel="mw:WikiLink" title="Rashidun army">army</a>?