support missions from the usual porter forces, water transport via canoe, and requisitioning from localities the army passed through. Movement of troops via canoes was critically important in the lagoons, creeks and rivers of the Niger Delta, a key area of Benin's domination. Tactics in the field seem to have evolved over time. While the head-on clash was well known, documentation from the 18th century shows greater emphasis on avoiding continuous battle lines, and more effort to encircle an enemy (ifianyako). Fortifications were important in the region and numerous military campaigns fought by Benin's soldiers revolved around sieges. As noted above, Benin's military earthworks are the largest of such structures in the world, and Benin's rivals also built extensively. Barring a successful assault, most sieges were resolved by a strategy of attrition, slowly cutting off and starving out the enemy fortification until it capitulated. On occasion, however, European mercenaries were called on to aid with these sieges. In 1603–04 for example, European cannon helped batter and destroy the gates of a town near present-day Lagos, allowing 10,000 warriors of Benin to enter and conquer it. As payment, the Europeans received items, such as palm oil and bundles of pepper. The example of Benin shows the power of indigenous military systems, but also the role outside influences and new technologies brought to bear. This is a normal pattern among many nations. Britain seeks control over trade Benin temporarily declined after 1700 after a civil war, then partially recovered later in that century, only to decline once again in the late 19th century. Benin's economy was previously thriving in the early to mid 19th century with the development of the trade in palm oil, and the continuation of the trade in textiles, ivory and other resources. To preserve the kingdom's independence, bit by bit the Oba banned the export of goods from Benin, until the trade was exclusively in palm oil. By the last half of the 19th century Great Britain had come to want a closer relationship with the Kingdom of Benin; for British officials were increasingly interested in controlling trade in the area and in accessing the kingdom's palm oil, kola nut, ivory and potentially rubber resources, following the introduction of Hevea brasiliensis saplings, via Kew Gardens, in 1895. Several attempts were made to achieve this end beginning with the official visit of Richard Francis Burton in 1862 when he