The anti-slavery movement was remarkable in that it got huge numbers of the British people to join in. This was because the campaigners tried to get their message across to the whole population, rather than to a narrow part of it. They did this by using different communication channels, in different ways, to reach different audiences.
The campaigners wrote complex arguments to persuade politicians and decision makers of the case for abolition but they also produced simple works, in a popular easy to read style and issued posters and voting guides. They used the arts - the anti-slavery poems from William Cowper, Samuel Taylor Coleridge and William Wordsworth, for example, proved popular. Below is an extract of a poem by William Cowper:
...."By our sufferings, since ye brought us
To the man-degrading mart,
All sustain'd by patience, taught us
Only by a broken heart.
Deem our nation brutes no longer,
Till some reason ye shall find
Worthier of regard, and stronger
Than the colour of our kind." ....
However, only about half of the British population could read. Therefore it was essential to find other means to get the message across. One way to do this was to take the campaign to the people, by talking directly to as many groups as possible. Campaigners such as Clarkson and Wesley travelled widely and gave impassioned speeches in halls, churches and even in the open air. Olaudah Equiano also toured the country to promote his autobiography at events organised by the various committees. Regular public debates were held, sometimes addressed by Africans, particularly in London.
The audience at these events varied widely, depending on the reason for the gathering and the location, from the rich and well educated to ordinary working people. Other campaigners engaged in door to door canvassing. Sophia Sturge, for example, personally visited 3000 homes during a sugar boycott in the 1820s, to engage support and explain what the campaign was all about.
The Campaigners also realised the importance of pictures and images. Cartoonists and artists, like JMW Turner and William Blake, provided pictures of slavery that reached audiences in ways the written word could not. However, the most important and powerful image came from a piece of evidence uncovered by Thomas Clarkson at Plymouth. It was a plan and section of a loaded slave ship. The ship was packed so full that it was hard to comprehend the sheer inhumanity.
The shocking diagram of the Brookes (a slave ship from Liverpool) became the defining image of the battle to end the slave trade. It showed 482 slaves lying shoulder to shoulder and, as Clarkson said, made "an instantaneous impression of horror on all who saw it". The printer, James Phillips, copied and published the image in April, 1789, and it was widely distributed throughout the campaign.
The campaign, however, went even further than this, to produce an especially commissioned image that would provide an identity for the campaign itself; today we would call this branding.