Panicked by Fire Attack

[Atraphoenix]

They were effective, but mainly fire arrows used in pillage missions to burn down houses, farms, etc.
for accuracy I do not think that generals favoured it. but in siege battles mainly to demotivate the defenders and also defenders used it to burn enemy's siege machines.
though it may be a fiction or a myth but there is a record that Syracusians used some unknown war machine that burned roman navy, I think they used mirrors to reflect the sunlight to burn the sails after sails burned so the navy was burned.
In roman records it is recorded like that but in the end they managed to capture the city.
but I think boiling oil must be more devastating effect on morale than fire arrows.
the famous general must be Edward, the Black Prince who was infamous for his "The Great Raid of 1355" on the Aquitaine–Languedoc Front, which crippled southern France economically, and provoked resentment of the French throne among French peasantry.