Some of the earliest regular foreign visitors to the islands were whaling vessels from Britain, the United States and Australia. They came for food, wood and water from late in the 18th century, establishing a trading relationship with the Solomon Islanders and later taking aboard islanders to serve as crewmen on their ships. Relations between the islanders and visiting seamen was not always good and sometimes there was bloodshed. A knock-on effect of the greater European contact was the spread of diseases to which local peoples had no immunity, as well a shift in the balance of power between coastal groups, who had access to European weapons and technology, and inland groups who did not. In the second half of the 1800s more traders arrived seeking turtleshells, sea cucumbers, copra and sandalwood, occasionally establishing semi-permanent trading stations. However initial attempts at more long-term settlement, such as Benjamin Boyd's colony on Guadalcanal in 1851, were unsuccessful.