We found, first in SW France and now in Greece, that a mattock (or a set of mattocks with varying blade widths) is ideal for working in tough ground - as most Mediterranean ground is, for most of the gardening year. In our Greek garden, which in the more natural parts is very unyelding, I have another tool which I find absolutely invaluable for extracting deep-rooted weeds from tricky situations, and for planting bulbs and corms in hard ground: this is a heavy-duty lorry tyre lever, basically a very strong iron shaft about 45 cm long, with a comfortable grip one end, and a "digging" blade about 2 cm wide at a slight angle the other end. If you want to find one, search for a 450mm soft grip pry bar.
I wouldn't be without either of these tools!