Arriving at Kujin, the Australians discovered that the centre span of the 300-metre (330 yd) concrete bridge had been demolished by KPA engineers, blocking their passage across the river.

In the ensuing fighting a convoy of KPA vehicles, including a tank, two jeeps, a motorcycle and about 60 infantry moved down the road towards A Company with the intention of re-occupying the ridges overlooking the river crossing.

The Australians ambushed the convoy at close range with small arms fire and mortars, forcing the KPA to flee after abandoning their vehicles with only the tank successfully shooting its way out.

Later another T-34 tank and supporting infantry pressed to within 10 metres (33 ft) of the B Company headquarters, before stopping and taking up a position between the ridges unaware of the location of the Australians.

[1] Numerically superior and better equipped, the KPA crossed the 38th Parallel and rapidly advanced south, easily overcoming the inferior Republic of Korea Army (ROK).

In response, the United Nations decided to intervene on behalf of South Korea, inviting member states to send forces to restore the situation.

[6] Australia was one of the first nations to commit units to the fighting, playing a small but sometimes significant part in the UN forces, which was initially led by General Douglas MacArthur.

As such, with a strength of nearly 1,000 men, the addition of 3 RAR gave the brigade increased tactical weight as well as expediently allowing the Australians to work within a familiar organisational environment, rather than being attached to a US formation.

[11] By the time 3 RAR arrived in the theatre, the KPA had been broken and were in rapid retreat, with MacArthur's forces conducting a successful amphibious assault at Inchon and breakout from the Pusan Perimeter on the southern tip of the Korean peninsula.

Although the KPA had suffered heavily in the preceding weeks, they continued to resist strongly, while a lack of accurate maps and the narrowness of the roads made rapid movement difficult for the advancing UN forces.

On 24 October, MacArthur had removed all restrictions on the movement of his forces south of the Yalu River and prepared for the final phase of the UN advance, defying a directive of the US Joint Chiefs of Staff and risking Chinese intervention in support of North Korea.

[19] With the Middlesex in the vanguard, the lead elements of the 27th British Commonwealth Brigade successfully crossed the Chongchon unopposed at Sinanju on 24 October using assault boats.

Following repairs the bridge was made available to the 27th British Commonwealth Brigade's light wheeled vehicles on 25 October, while the accompanying Sherman tanks located a ford 4.8 kilometres (3.0 mi) upstream, and were able to cross the Chongchon at that point.

[23] That afternoon Coad ordered 3 RAR to resume the lead and continue the advance towards Pakchon, the next major town 15 kilometres (9.3 mi) north on the Taeryong River.

[22] A United States Air Force (USAF) LT-6G Mosquito light spotter aircraft scouting beyond the western bank subsequently reported the presence of two KPA companies to the north, overlooking the bridgehead.

[26] A and B Companies were then instructed to prepare to assault the KPA positions on the western bank; however, the approach of dusk prevented a second airstrike and a fire plan was subsequently arranged by the American artillery and the battalion mortars before a more substantial thrust across the river was launched by the Australians.

[22] D Company subsequently returned at 18:30, bringing 225 prisoners with them after leaving a platoon to guard the American engineers which had begun constructing a ford from a damaged underwater bridge for use the following day.

[30] Again using the broken span, the Australians crossed the river and scaled the bank in the moonlight, before establishing defensive positions on both sides of the road on the crest 400 metres (440 yd) from the Taeryong.

Unchallenged, the Australians suspected that the KPA had withdrawn and, still largely without winter clothing, they then began to dig-in amid a sub-zero wind which blew in from Manchuria, 97 kilometres (60 mi) away.

[27] Shortly afterwards, at 19:30, B Company detected a KPA force of around company-size preparing for a frontal assault, and called-in mortar fire to break up their formations, while a number of forward patrols had to be withdrawn by the Australians in order to prevent their encirclement.

[33] Half an hour later KPA shells hit the 3 RAR battalion headquarters and C Company positions on the other side of the river, however the rounds landed in the damp soil of the paddy field and failed to explode.

A wounded soldier fell into the fast flowing Taeryong River and the 3 RAR battalion drum-major, Sergeant Thomas Murray, subsequently dived into the freezing waters and rescued him.

[18] In the ensuing fighting a convoy of KPA vehicles, including a T-34 tank, two jeeps, a motorcycle and about 60 infantry moved down the road towards A Company with the intention of re-occupying the ridges overlooking the river crossing, likely unaware of the Australian dispositions.

[18] Among the KPA dead was the commanding officer of the Reconnaissance Unit of the 17th Tank Brigade, Lieutenant Colonel Kim In-sik, who was carrying a number of marked maps and documents.

[37] Later another KPA T-34 tank and supporting infantry pressed to within 10 metres (33 ft) of the B Company headquarters, before stopping and taking up a position between the ridges still unaware of the location of the Australians.

[39][Note 1] Regardless, despite using infantry mounted on tanks the KPA seemed unable to conduct the sort of organised or co-ordinated assault required to dislodge the Australians, and they were relatively untroubled for the rest of the night.

[41] In spite of harassment by the KPA during the previous evening which had cost D Company four casualties, the American engineers at Pakchon had continued to work on the underwater bridge and the Sherman tanks were able to cross there by 11:00 that morning, although the water was still considered too deep for wheeled vehicles.

Undetected by US and South Korean intelligence, the 13th Army Group crossed the border on 16 October and penetrated up to 100 kilometres (62 mi) into North Korea.

That morning a spotter aircraft reported a large KPA formation consisting of a battalion-sized force of 500–600 infantry supported by several tanks and at least two self-propelled guns, positioned on a thickly wooded ridgeline around Chongju.