He asked Valcke to maintain complete secrecy about the proposed enterprise, and to be patient and flexible with Henry Morton Stanley, whom he described as being a brilliant explorer and energetic organizer, but with a difficult and ambititious character.

Stanley explained that his task was to build a road that would pass the foot of the Ngoma plateau and make it possible to transport equipment, provisions and personnel to establish stations in the Congo territory.

[2] Stanley wrote of Valcke's work, "Though our young friend is frequently suffering from dysentery, by the time he is through with his task, we have finished off our causeway, have levelled it with 24 inches of earth, and a fine compact broad wagon road is the result, along the base of which the baffled river lashes itself into fury.

He charged Charles-Marie de Braconnier with building a road from Manianga to the mouth of the Lufu River, bypassing the Ntombo-Mataka falls.

Valcke entrusted Isanghila to Eugène Janssens and Frédéric Orban, and joined Stanley in Manianga on 14 July 1881.

They left the next day with a contingent of native auxiliaries along the route marked out by Braconnier carrying the En Avant and two whalers they intended to launch at the Stanley Pool.

There they were informed that Pierre Savorgnan de Brazza had signed a treaty with Chief Makoka and claimed possession for France of the whole right shore of the Congo River north of the Pool.

[2] In Brussels Valcke met King Léopold II, who agreed that it was necessary to move fast to occupy Central Africa.

On 8 February 1882 Valcke left for Zanzibar to recruit auxiliaries and bring them to Banana via Cape Town, where he was joined by Alphonse van Gèle.

In the meantime, Stanley had undertaken a tiring expedition to the Mfini and Lake Léopold II, where he came down with fever and abdominal pain and was ordered to return to Europe.

Orban fell ill and Valcke took over the job of carrying the steamer to the Pool, where it would be reassembled ready for Stanley's next expedition in May 1883.

The chiefs Mfumu Ntaba, Ngaliema and Gantschu accepted the authority of the AIA and consented to European posts being built in the interior and on the river between the mouths of the Lefini and the Djoué.

[1] Léopoldville was developing fast when word came of troubles at Manyanga and Stanley sent Valcke there with an escort of 45 Zanzibaris to restore order.

Valcke was joined at Vivi by the English General Sir Frederic John Goldsmid, who had been sent by the king to conclude the same treaty, and who confessed himself unqualified for the task.

Valcke started to organize a caravan of 250 Zanzibaris to carry the equipment and 15,000 loads of food and goods weighing 65 pounds (29 kg) each.

[2] Sir Francis de Winton mediated with Stanley, who gave back the Zanzibaris to Valcke, and with many difficulties the caravan reached Isanghila on 4 September 1884.

Valcke suffered from another bout of hematuria, but pressed on and the seven boat sections and the boilers reached Lutete on 14 February 1885.

The Zanzibaris bridged the river and carried all he equipment across on the evening of 13 March, but some of them deserted that night leaving only 82 men with Valcke.

She was accompanied by a young Flemish servant and settled in a comfortable house by the standards of the time in the capital of the state, Boma.

On 8 August 1887 Valcke and Thys directed transport of five carts weighing 1,500–3,500 kilograms (3,300–7,700 lb) to Stanley Pool, which took hundreds of local laborers a month to achieve.

[2] The heavily loaded carts carried spare parts for the Roi des Belges and Ville de Bruxelles boats.

[6] In 1888 Valcke and the engineer Fabry reported the general route of the railway based on a sketch map drawn up by Thuys.