Chord/Tab song: Theme for an Imaginary Western

The chords I could get by ear. Since I needed the chords written and I couldn't find any
score nor tablature for this song, I posted what I could get. NOTE: The "?" is a chord
which I'm sure it's there but I can't figure it which is it. It's the same chord through
the whole song. Any corrections is welcomed.

INTRO: G Bm Em

When the [G]wagons[Bm] leave the [Em]city
for the f[A]orest, and further [F]on
Painted w[G]agons[Bm] of the [Em]morning
dusty r[A]oads where they have [C]gone
Sometimes [G]travellin[Bm]g through the[Em] darkness
met the [A]summer coming [F]home
Fallen f[G]aces[Bm] by the [Em]wayside
C ? G Bm
Looked as if they might have known
( Tab from: http://www.guitartabs.cc/tabs/j/jack_bruce/theme_for_an_imaginary_western_crd.html )
O the [Em]sun was in [Bm]their eyes
and th[Em]e desert that [Bm]dries
In the [C]country [G]towns
where the [A]laughter [Em]sounds[B][C]

O the [G]dancing[Bm] and the [Em]singing
O the [A]music when they [F]played
O the [G]fires[Bm] that they [Em]started
O the [A]girls with no [C]regret
Someti[G]mes they found it[Bm]
Sometimes they [Em]kept it
Often [A]lost it on the [F]way
Fought each [G]other[Bm] to pos[Em]sess it
C ? G Bm
Sometimes died in sight of day

O the [Em]sun was in [Bm]their eyes
and th[Em]e desert that [Bm]dries
In the [C]country [G]towns
where the [A]laughter [Em]sounds[B][C]

OUTRO: G Bm Em A F G Bm
Em C ? G