On 31 March 1886 a steam tender of the African Direct Telegraph Company (a subsidiary of John Pender's Eastern Telegraph group) landed the first armoured submarine cable on Lagos Bar, splicing the colony into a copper line that already ran Bathurst–Freetown–Accra. A second cable extended east to Bonny and Brass on the Niger delta in 1893. For the first time a message from Lagos could reach London in under three hours instead of the six weeks an Elder Dempster mail steamer required. The cable terminus, a small zinc-roofed cable hut on the Marina near the present-day CMS bus stop, was the first piece of telecommunications infrastructure ever built on Nigerian soil.
Inland telegraphy followed the railway. The Lagos–Ibadan line opened with the railway in 1901; the trunk extended to Jebba (1909), Kano (1912) and Maiduguri (1964). The colonial Post and Telegraph Department — P&T, the institutional ancestor of NIPOST and NITEL — operated Morse key offices at every district station; the telegraph clerk, often a Sierra Leonean or Gold Coast Krio, was for fifty years the highest-paid African on the District Officer's payroll. By 1930 Nigeria had 174 telegraph offices and a working national telegram system that processed roughly 2.4 million telegrams a year — more traffic than the post office handled letters.
The technology was decisive in three ways colonial historians rarely credit. (1) It made the 1914 Amalgamation administratively possible: Lugard could not have governed Northern and Southern Nigeria as one unit without the telegraph trunk to Zungeru and Kaduna. (2) It collapsed produce arbitrage — palm-oil prices at Burutu, cocoa prices at Ibadan and groundnut prices at Kano now moved with the London market the same day, transferring price-discovery power from African middlemen to expatriate buying agents. (3) It built the first cohort of African telecommunications technicians, the P&T-trained signallers who would become the founding staff of NITEL in 1985.
Adoption lag: UK first commercial electric telegraph (Cooke–Wheatstone) 1837 → Lagos cable 1886 = 49 years. UK first national network c. 1860 → Nigerian P&T network c. 1912 = 52 years. The lag held steady at half a century — and would widen for every technology after this.