Help forming 2-inch-thick concrete walls

[brianwelch]

I poured a sonotube 12" x 30" column to support a deck post.   I drove in four rebars to the ground and attached some light gage fence wire to the four rebars. 

I was not working on any instructions, so that might have been unnecessary, but like chicken soup, "it can't hurt".

I simply assumed that the concrete needed reinforcement.  I did not read that anywhere.

Concrete has very little tensile strength, so it needs reinforcement when loaded in tension (or subject to flexing/bending), not necessarily in compression if adequately sized...