The followers of Bokero's movement were poorly armed with spears and arrows, sometimes poisoned. However, they were numerous and believed that they could not be harmed because the Germans' bullets would turn to water. They marched from their villages wearing millet stalks around their foreheads. Initially, they attacked small outposts and damaged cotton plants. On 31 July 1905, Matumbi tribesmen marched on Samanga and destroyed the cotton crop as well as a trading post. Kinjikitile was arrested and hanged for treason. Before his execution, he declared that he had spread the medicine of the rebellion throughout the region. On 14 August 1905, Ngindo tribesmen attacked a small party of missionaries on a safari; all five, including Bishop Spiss  were speared to death. Throughout August the rebels moved from the Matumbi Hills in the southern part of what is now Tanzania and attacked German garrisons throughout the colony. The attack on Ifakara, on 16 August, destroyed the small German garrison and opened the way to the key fortification at Mahenge. Though the southern garrison was quite small , their fortifications and modern weapons gave them an advantage. At Mahenge, several thousand Maji Maji warriors  marched on the German cantonment, which was defended by Lieutenant Theodor von Hassel with sixty native soldiers, a few hundred loyal tribesmen, and two machine guns. The two attacking tribes disagreed on when to attack and were unable to co-ordinate. The first attack was met with gunfire from 1000 m; the tribesmen stood firm for about fifteen minutes, then they broke and retreated. After the first attack, a second column of 1,200 men advanced from the east.  Some of these attackers were able to get within three paces of the firing line before they were killed.
Question: What did the two tribes disagree on concerning their attack on the German cantonment?
Answer: when to attack