Why the delay.

Why was there such a long delay between the Battle of Isandlwana and Chelmsford’s return to Isandlwana.
The battle started in the morning ,but Chelmsford’s Colum did not arrive back until it was dark.
Was there a reason for this. Was he to far away.

Chelmsford was 10 kilometres away when the Zulu Impi attacked and, due to the hilly terrain, had such a poor view of the camp he even dismissed reports of the attack when they reached him.
It was not until early afternoon that he became convinced that something had gone seriously wrong; by the time he had collected his command and marched back to Isandlwana, it was dusk. The battle was long over, and the last Zulus could just be seen retiring over the iNyoni heights. Chelmsford’s men reoccupied the camp in the darkness, stumbling over bodies in the devastation.

1879. The morning of the disaster at Isandlwana, Lieutenant Milne served as naval aide-de-camp to Lord Chelmsford during the Anglo-Zulu War
Milne left the ill-fated camp with Chelmsford's column.

Lieutenant Milne climbed to the top of a hill or tree to observe the movements at the camp of Isandlwana with his eye-glass when the first reports of a Zulu attack began to trickle in.
Milne reported that the draught oxen appeared to have been moved into the camp but that all else looked normal. The "oxen" were in actuality the mass of Zulu warriors who by that time had
overwhelmed the camp and its garrison.

So at what time did Chelmsford actually realise the camp had been attacked.

After his meeting with Lonsdale, Chelmsford formed up the N.N.C. and advanced towards the camp. The mounted infantry went forward to reconnoitre and they came back with a report of Zulus swarming amongst the tents. Gosset reached the new camp site at about 16h00 but it was after 18:00hrs by the time Glynn's forces arrived. The men had been marching all day and were very tired. Forming up the troops with the guns in the centre, the regular infantry on either side, a battalion of N.N.C. on each side and mounted men on the flanks, Chelmsford moved forward to near the Conical Kop. Night had almost fallen and all that could be seen were the silhouettes of the wagons in the saddle and some Zulus disappearing over the escarpment. Four rounds were fired into the wagons but as no response was observed Major Black advanced with three companies of the 24th to occupy the Koppie which now bears his name.

The whole force now moved up to the col where it arrived at 21:00hrs . It was obviously impossible to pitch camp and the men had to sleep on the ground wherever a space could be found. Many encountered the bodies of their comrades when groping for a place to lie down. To make matters worse firing could be heard and the glow of flames above Rorke's Drift could be seen. Before dawn the force marched away from the bloody field but as they approached the Batshe River the Zulus who had attacked Rorke's Drift emerged from a valley to their left barely 400 metres away. No action was taken as the Zulus were probably even more exhausted than Chelmsford's men, while the latter did not have sufficient ammunition to become involved in further hostilities.

From: Military History Journals

Milne's own words.

lieutenant Milne says : " On reaching the summit I could see the
camp ; all the cattle had been driven in close around the tents. I could
see nothing of the enemy on the left "
"We are not quite certain about the time. But it is just possible that
what I took to be the cattle having been driven into camp may possibly
have been the Zulu ' impi ' "

It is quite impossible to comprehend the extraordinary infatuation of the General and (apparently) his staff in seeing "nothing unusual" in
this. The General says he had " no cause, therefore, to feel any anxiety about the safety of the camp." His Military Secretary says "not a sus-picion had crossed my mind that the camp was in any danger ; " and yet a written message told that a Zulu force had appeared on the left front of the camp — unreconnoitred ground, where the General himself on the previous afternoon had seen several Zulu horsemen : and now his A.D.C.
reports what is one of tixeßrst and surest signs of danger in South African warfare :—"that the cattle had been driven into camp

Thinking about the situation. What could Chelmsford had done if he had returned to Isandlwana during the attack on the camp. I not sure how much ammunition he had with him ,as most of the ammunition was held at Isandlwana.