The mission of the American evangelists, D. L. Moody and Ira D. Sankey, was one of the great public events of mid-Victorian Britain. Between June 1873 and August 1875, the Congregationalist preacher and his Methodist singing partner filled the largest public halls of England, Scotland and Ireland, with audiences of up to 20,000. In these two years several million people heard the revivalists, and Moody and Sankey established themselves as the greatest mass communicators of their generation. In London alone, it was estimated that the aggregate attendance at their meetings was two and a half million, and according to the Daily Telegraph they had converted the capital's largest building, Islington's Agricultural Hall, ‘into an open church’. Sankey's hymn book – later to sell between fifty and ninety million copies worldwide – earned the evangelists £7,000 in royalties while they were still in Britain, though it sold for only sixpence. Even the messenger boys were singing Sankey's songs in the streets, and the title of one of his most popular pieces entered the language as a common expression: ‘Hold the fort’. The popularity of the evangelists was so great that continental newspapers commented on the phenomenon, whilst the provincial and national press in Britain devoted hundreds of columns to reports of the revival meetings. People as diverse as George Bernard Shaw, Matthew Arnold and Friedrich Engels criticised the American visitors and their audiences, and even Queen Victoria was not amused by their antics. The New York Times concluded that ‘the Moody and Sankey fever’ could only be accounted for ‘on the theory of the gravedigger in Hamlet, that in England everybody is mad’.