Congregationalist losses to Presbyterianism increased greatly in the decades in which the "Plan of Union," was in effect. Although it was designed by Connecticut Congregationalists and the Presbyterian General Assembly to avoid duplication of effort in evangelizing the frontier regions, this plan resulted in numerous Congregational-founded parishes being annexed to presbyteries, usually through the pastor's affiliation and often without the local church's assent. The need to dissolve that failed attempt at inter-denominationalism, which had already taken place among the Presbyterians, prompted a national gathering of Congregationalists in 1865 at Boston, Massachusetts. This was the first national meeting in more than 200 years, since the 1648 synod that produced the Cambridge Platform, a confession of faith similar to the Presbyterians' Westminster Confession. It was not until 1870, though, that a sufficient number of Congregationalists responded to a related call to organize nationally.