On the morning of the 18th October No. 4 Column launched an assault on the enemy positions in order for No. 3 Column to effect a junction with the isolated Nigerian Brigade.  No. 4 Column’s attack was at first successful, the 30th Punjabis drove the enemy from their trenches and occupied them, while parts of the 3/4th King’s African Rifles and the 259th Machine Gun Company came up on the Punjabis’ left to strengthen that flank, thus allowing No. 3 Column to successfully effect a junction with the Nigerians at 8 o’clock.  The enemy however was in force and delivered a strong counter-attack on the column’s left, which eventually compelled the British line to fall back to the river bed, this defensive position was maintained during the afternoon and further German attacks were repulsed.  No. 3 Column meanwhile attacked the enemy’s left flank and forced it back for some distance with the 3/2nd King’s African Rifles leading the assault but yet another ferocious German counter-attack was launched which resulted in a gap emerging between the fronts of the two British columns.

At 3.40 that afternoon the 126 men of the 25th Royal Fusiliers, by now attached to No.4 Column, were ordered forward to fill this gap (marked Y on the sketch map).  Whether accidentally mistaking the intended direction or intentionally altering course to assist the 3/2nd King’s African Rifles the battalion swung to the right. Instead of charging down upon the German troops opposing No.4 Column the men of the 25th Royal Fusiliers came up on the left flank of No.3 Column’s extended line and ended up advancing towards the wrong German entrenched positions.  In so doing they passed in front of a number of German machine guns, the result of which was devastating, the battalion was cut to pieces, leaving behind a trail of dead and wounded men, others rushed forward into clumps of dense bush but were there stopped by fire and a German askari bayonet attack.  A few survivors fought their way back to the British positions but the battalion was to emerge from the action with fewer than 50 men.

While the 25th Royal Fusiliers were attempting to fill the gap between the attacking fronts of the two columns the enemy also developed another strong counter-attack and it was found necessary to restore the situation by bringing up the 3rd Nigerians from reserve to the left of No.3 Column.  Enemy pressure continued until dark, but without further result, and on the morning of the 19th it was found that the Germans had retired.

The action at Nyangao, or Battle of Mahiwa as it is often referred to, was an unusual occurrence in the war in East Africa as, for probably the only time during the entire campaign, the German Schutztruppe forces were committed in sufficiently large numbers to stand and fight the opposing British force rather than adopt their more usual, hit and run, guerrilla style tactics.  British casualties suffered during the course of the action were significantly higher than the Germans but, as a percentage of the force committed, were comparable and with his resources dwindling von Lettow-Vorbeck, perhaps feeling his losses more keenly, ceded German East Africa to the British as he took what was left of his force over the border into Portuguese East Africa.

In a head to head combat that had resulted in the fiercest and bloodiest fighting of the campaign with both sides repeatedly attacking each other in thick bush over a number of days, the action at Nyangao, on 18th October 1917, was to be the 25th Battalion Royal Fusiliers’ final action of the war.