A number of peace symbols have been used many ways in various cultures and contexts. The dove and olive branch was used symbolically by early Christians and then eventually became a secular peace symbol, popularized by a Dove lithograph by Pablo Picasso after World War II. In the 1950s, the "peace sign", as it is known today, was designed by Gerald Holtom as the logo for the British Campaign for Nuclear Disarmament (CND), a group at the forefront of the peace movement in the UK, and adopted by anti-war and counterculture activists in the US and elsewhere. The symbol is a superposition of the semaphore signals for the letters "N" and "D", taken to stand for "nuclear disarmament", while simultaneously acting as a reference to Goya's The Third of May 1808 (1814).