Nassau Bay.

The 162nd US Regiment landed at Nassau Bay on the night of the 29/30
June and next morning moved out of the bridgehead. On 1 July the
easternmost company of the 2/6th Battalion advanced to the coast along
the south arm of the Bitoi River, driving off a company of Japanese. On the
morning of the third day ashore, 2 July, the main American force
remained clustered round the beach, but that afternoon one company
advanced to the Bitoi. Next day four 75-mm guns were landed at Nassau, a
most important reinforcement, and by the 4th more than 1,400 troops were
ashore. Papuan soldiers advancing along the coast ahead of the 162nd US
Regiment reached Lake Salus on 9 July and then pushed on to Tambu Bay.

On the morning of 7 July the 2/6th had attacked Observation Hill and by
nightfall held most of it. Next day the leading Australian company
advanced a stage farther towards a creek where it was to link with the
Americans from the Bitoi. On the 9th, now supported by the American
field guns whereas formerly there had been only two mountain guns behind
them, five Australian companies pressed on with aggressive patrols
until, on the 10th, only seventy-five Japanese survived in the area, and
their line of retreat was cut. On the 12 May the Pimple was occupied. On
13 May there was a general advance and on 14 May Mubo airfield and Green
Hill were taken. The Japanese still stoutly defended Old Vickers where
they were strongly dug in to defend the track to Salamaua and on 7 and 9
July stopped attacks by the 58th/59th Battalion.

The US III/162nd Battalion (Major Archibald B. Roosevelt) was assembled
at Nassau Bay by 12 July as a preliminary move to establish artillery at
Tambu Bay. On the 21st the American battalion reached Tambu Bay and
supplies were being unloaded there. The Americans' task was to capture
Scout Ridge, overlooking the bay. Attacks on the 22nd failed and a
second battalion (the US II/162nd) was sent into reinforce the attack.

On 16 July a company of the 2/5th Battalion had assaulted Mount Tambu
with great dash and captured all but the main northern knoll. The
Japanese counter-attacked again and again that night, supported by
mortar bombs and shells from a mountain gun. A second company reached
the area next morning. On the night of the 18 May the Japanese attacked
and almost encircled the two Australian companies on Tambu, and next day
a fierce struggle developed. By 2.30 pm, after much slaughter of the
Japanese, they accepted defeat and left the Australians in possession of
the southern slopes. Farther north, on 15 July, after mortar and
Vickers-gun fire, two platoons of the 2/3rd Independent Company attacked
Ambush Knoll south of Namling, while the 58th/59th Battalion attacked
towards Bobdubi in another effort to cut the Japanese communications.
One platoon of the Independent Company drove the Japanese from their
forward positions, the other thrust them from Orodubi, and that night
the Japanese abandoned Ambush Knoll. The attack by the 58th/59th was
upset, however, by Japanese counter-moves. In a renewed attack on the
17th the Independent Company again carried out its task but the
58th/59th was held up.

The establishment of the Nassau Bay base had made it possible to bring
in and supply a substantial quantity of artillery. By 23 May two US
field artillery battalions, two Australian field batteries, the 1st
Australian Mountain Battery, the 2/6th Australian Survey Battery, and
four anti-aircraft batteries were in place. On the right flank the
American regiment was still making little progress. In the fourth week
of July the US II/162nd battalion completed its arrival at Tambu Bay and
was given the task of capturing 'Roosevelt Ridge' as it was now named.
The battalion attacked and gained and held a foothold on the ridge. The
Japanese were well dug in and not to be driven out by frontal attacks.
Roosevelt's battalion, aided by Papuan patrols, was now employed cutting
the enemy's supply route to the west.

On 28 July a flanking attack by a company of the 2/6th took a feature
forward of Ambush Knoll. The same day 58th/59th Battalion supported by
artillery, mortar and machine-gun fire at last took the stubborn Old
Vickers position and drove the Japanese from Bobdubi Ridge. It was
estimated that in the six weeks to 6 August, the 15th Brigade had killed
400 Japanese for a loss of forty-six killed and 152 wounded, an
indication of the increasing tactical superiority of the attackers.

The leading battalion of the 29th Australian Brigade, the 42nd, was
moved forward into the Nassau Bay area and thence marched northward and
at length went into position between the Americans on the right and the
17th Brigade, of which it became part. As a preliminary to the capture
of Mount Tambu the 42nd Battalion occupied Davidson Ridge between Tambu
and Roosevelt Ridge. Then on 13/14 August the II/162nd Battalion took
Roosevelt Ridge after a heavy artillery barrage which bared it of
vegetation. The 15th Brigade's attack opened on 14 August. Twenty-nine
heavy bombers accurately bombed Coconut Ridge with devastating effect,
and guns, mortars and machine-guns brought down a barrage. A company of
the 2/7th Battalion then attacked up a cliff so steep that the men had
to crawl on hands and knees, but by early in the afternoon they had
gained the North Coconuts position. On the night of the 16/17 August the
Japanese abandoned South Coconuts.

The 2/6th Battalion opened its attack on Komiatum Ridge on 16 August.
After about 500 shells had been fired into the Japanese positions two
companies attacked and in twenty-five minutes had occupied the
objective. The enemy in the Mount Tambu area were now surrounded, their
routes to the north being cut on Komiatum and Davidson Ridges. It was
expected that lack of rations (patrols had discovered they were
delivered every three days) would cause the Japanese to attempt the
break out on the third night. On 19 August patrols of the 2/5th found
Goodview Junction deserted and US I/162nd Battalion occupied Tambu
without opposition.

The 15th Brigade now pressed in towards the track leading to Salamaua.
On 17 August after a bombardment two platoons of the 2/3rd Independent
Company advanced; one occupied the junction of the Bobdubi-Salamaua
track and another track from the south without opposition, but the other
was held. Heavy fighting developed, the Japanese launching strong
counter-attacks. On 19 August Savige ordered that every effort must be
made to close the enemy's avenues of escape between Komiatum and Bobdubi
Ridges. Next day the brigade attacked on a wide front, and the 58th/59th
succeeded in cutting the Komiatum track in several places.

In preparation for the new offensive, Savige was instructed that his
force should be so organised that by 28 August it could be maintained
from the sea without air supply. From 21 August the 29th Brigade began
to relieve the 17th Brigade (excluding the 2/7th Battalion attached to
the 15th Brigade) which had been fighting its way through the
jungle-clad tangle of mountains from Wau towards Salamaua since January.
The Australians rapidly advanced towards Salamaua but Savige ordered
that the Japanese were not to be pressed so hard that would cause an
early evacuation of Salamaua.