The opening phase of the advance went spectacularly well against numerically superior opposition in difficult and hostile terrain and climate, most of the Ottoman forces fleeing or surrendering with comparatively little fighting. Townshend began his advance on 31 May 1915 when he had his 18-pounder artillery guns open fire on the Ottoman trenches while his men in the "bellums" outflanked the Ottoman positions. He called his advance on Amarah "Regatta Week" as his fleet began what he called a "vigorous and rapid pursuit by the naval flotilla on Amarah". He had a very low opinion of the Marsh Arabs whom he regarded as "great scoundrels and even murderers" good only for looting, and he dismissively referred them as the "Salvation Army".