1942 The Battle of Banjarmasin (31 January – 10 February 1942) took place as part of the Japanese offensive to capture the Dutch East Indies.

The Unit would then traverse the jungle and mountains southward, with an element of its force advancing as vanguard to block any Dutch ambush attempts.

To secure passage through the channel west of Laoet (Laut) Island, Okamoto planned to conduct a night raid on Kotabaroe (Kotabaru) to gather supplies and intelligence.

[14][15] A major loss occurred on 27 January, when eight Glenn Martin bombers stopped by at Oelin en route to the Samarinda II Airfield.

Michielsen had set up a camp with food supplies 20 km east of Tanahgrogot to accommodate the evacuees, who now had joined the ranks of retreating soldiers.

As they advanced southward to Banjarmasin, the Land Drive Unit had to contend with the lack of adequate road, which rendered their motor vehicles and 600 bicycles useless.

They climbed up steep mountains and crossed makeshift log bridges over deep gorges, while fending off attacks from mosquitoes, leeches and other insects.

Under Halkema's orders, the Landwacht brigades in Tandjoeng (Tanjung), Amoentai and Barabai scorched the city and retreated without a fight.

Haga perceived the destruction to be premature, as it would disrupt the economic life in the cities along the Hoeloe Soengei (Hulu Sungei/Sungai), which refers to the line of towns and villages located east of the Barito River.

[18] At Dajoe, Lt. van der Poel's troops destroyed the small airfield in the town before retreating up north to Boentok (Buntok) and lost communication with the command staff.

When the local population mistakenly reported that the Japanese forces are advancing on the town, many of van der Poel's indigenous soldiers and field police deserted, leaving him with five men.

On 7 February, Halkema reinforced the troops at Kandangan with two brigades from Oelin (armed with a Madsen machine gun) under the command of 1st.

By 11:30, Remmert's troops arrived in Kandangan and began to take up position north of the town, before assisting Scholte in the demolition effort.

[2]Two days earlier, ter Poorten had commissioned Doup as a lieutenant-colonel and appointed him as Halkema's successor, citing the latter's health status (rheumatism) and mental imbalance.

Doup left Surabaya on 8 February, but as his plane reached the coast of Borneo at 01:00, he saw large fires on the mouth of Barito River, where Banjarmasin would be.

Oonincx refused to land; the failure to make contact is due to the destruction of the radio station at Oelin Airfield.

After sending out the destruction orders, Halkema and a few staff officers drove to Oelin Airfield to hand over command to his successor.

Both ships were directed to steam towards Schans van Tuyl (junction of the Martapoera (Martapura) and Barito River), where they will await further instructions there.

[20] From Schans van Tuyl, Irene and Otto eventually headed towards Java, taking Dutch refugees from Banjarmasin and part of Halkema's staff with them.

[1] After seeing Doup's plane left, Halkema drove in the direction of Takisoeng, where he arrived on the mouth of Barito River on 9 February.

After boarding Halkema, the ship then received a telegram from Bandung, ordering them to head west to Kotawaringin and wait for further instructions there.

[21] The Borsumij ship steamed on at 19:00; Dutch forces onboard that managed to evacuate to Kotawaringin at the time only numbered at 75 troops.

[25] Okamoto's Sea Drive Unit left Balikpapan on the evening 30 January on four large and two small landing crafts and began to make their way along the coast southward.

On 14 December 1943, he died in jail after being tortured for conspiring to bring back Dutch rule into Banjarmasin through an armed uprising, in what is to be known as the "Haga Plot".