Ok So there are two ways to play this song.

I saw one way that has a C#m in it and that is unnecessary! The basic chords to this 
are:

A, D, and E

The first way to play this song is to play these chords either open or with bar chords 
chords sound better, in my opinion):

Intro: A (for two measures), D, E      x2

           A (x02220@1)DE
If I had a hammer
                 A (x02220@1)DE
I'd hammer in the morning
                  A (x02220@1) DI'd (xx0232@1)hammer in the evening
              EAll (022100@1)over this land
              AI'd (x02220@1)hammer out danger
                 D(or (xx0232@1)D7)
I'd hammer out a warning
               D (xx0232@1)   A (x02220@1)       D (xx0232@1)             AI'd (x02220@1)hammer out love between my brothers and my sisters
D (xx0232@1)E (022100@1)        AD EAll (022100@1)over this land

End: A D A.

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The second way is with a capo on the 2nd fret:

Intro: G (held for two measures), C, D   x2

           G (320003@1) CD
If I had a hammer
                 G (320003@1) CD
I'd hammer in the morning
                  G (320003@1) CI'd (x32010@1)hammer in the evening
              DAll (xx0232@1)over this land
              GI'd (320003@1)hammer out danger
                 CI'd (x32010@1)hammer out a warning
               C (x32010@1)   G (320003@1)       C (x32010@1)             GI'd (320003@1)hammer out love between my brothers and my sisters
C (x32010@1)D (xx0232@1)       G (320003@1)CD
All over this land

End: G C G.

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Either Way is easy and sounds good. I have performed this song with a friend of mine 
the second way and me using the first. Listen to the song for strumming and phrasing. Have 
Comment with comments (haha) or correctins. :]