It is because of poverty that we first began to associate soda bread with the Irish, soda bread is one of the easiest kinds of bread you can make and in poor Irish households, soda bread was a cost effective staple of the dining table.
The Irish also liked that fact that soda bread was very easy to make when compared with making 'normal' bread, there was no need to prove or knead the dough and soda bread can be made with any kind of flour, you also didn't need an oven.
Legend has it that the traditional reason for cutting a cross into the top of the bread, was to 'let the devil out' whilst it was baking, although it did also allow the heat to penetrate the thickest part of the bread, which assisted when cooking.
In 1850, an Irish Medical Journal (Dublin Quarterly Journal of Medical Science) published an article on the use of soda in the preparation of bread, around the time of the great potato crop failures that contributed towards the Great Irish Famine.
During the failure of the potato crop, a large quantity of bicarbonate of soda was employed by the poorer classes in the preparation of bread.
The journal noted that during the mid 1800's, the Irish were making so much soda bread that bicarbonate of soda almost doubled in price, not only was soda bread cheap, it was also delicious when freshly baked and hot from the oven.
If you only had access to very poor quality wheat, you would add bicarbonate of soda to the mix in order to improve the texture and taste of the bread, it also made the bread less likely to break up and was considered to be just as wholesome as 'normal' bread, although these days most Irish soda bread is made with high quality wheat (even tastier).
By the late 1800's soda bread became hugely popular in Ireland, a popular journalist (Newry Telegraph) wrote a glowing article about the benefits of eating Irish soda bread, he wrote "there is no bread to be had equal to it for invigorating the body, promoting digestion, strengthening the stomach, and improving the state of the bowels.