Grenades, as we know them today, were not widely used during the 15th and 16th century for a number of reasons. One of the main reasons is that the technology for creating and using grenades did not yet exist during this period. The first hand-held grenades were developed in the late 16th century, and these early versions were relatively simple devices that were filled with gunpowder and had a fuse attached.

Additionally, the tactics and strategies of warfare during the 15th and 16th centuries did not yet involve the use of grenades. The primary method of warfare during this period was still armored knights charging on horseback and infantry armed with pikes, swords and bows. The use of firearms had not yet become widespread, and the technology for creating effective firearms was still in its early stages.

Furthermore, the cost and complexity of producing grenadiers and the grenades themselves were not yet viable, only a few armies could afford and maintain them.

It's worth to mention that there were some examples of early versions of grenades being used during this period, but these were relatively rare and not yet widely adopted by military forces.

It wasn't until the 17th century that grenades started to be used more widely in warfare.

During the colonial period, European powers invading and occupying countries in Africa, Asia, and the Americas was a common occurrence, and these actions were often met with little or no condemnation from other countries or international organizations. This was due in large part to the prevailing belief at the time that European nations were culturally and technologically superior to the peoples they colonized, and that it was therefore justifiable to bring these "uncivilized" peoples under European control.

As for the reactions to specific wars, it would depend on the time, the context, and the country involved. For example, during the late 19th and early 20th centuries, many European powers had significant economic and political interests in Africa, and the Scramble for Africa was met with little resistance from other countries, as the European nations were seen as the dominant powers of the time.

However, as the 20th century progressed, there were increasing calls for decolonization and self-determination from the colonized peoples, and the actions of European powers in Africa and Asia began to be met with more widespread condemnation. The United Nations, which was established in 1945, was one of the key organizations that helped to coordinate the decolonization process and promote the rights of colonized peoples.

There are many books and articles that have been written about the history of colonialism and its impact on the colonized peoples. Some books that might be of interest include:

"The Scramble for Africa" by Thomas Pakenham

"The Empire Writes Back: Theory and Practice in Post-Colonial Literatures" by Bill Ashcroft, Gareth Griffiths and Helen Tiffin

"Decolonizing the Mind: The Politics of Language in African Literature" by Ngugi wa Thiong'o

"The Wretched of the Earth" by Frantz Fanon

"A History of Africa" by J.D Fage and William Tordoff

These are just a few examples, and there are many more books and resources available on this topic. It's important to remember that this period of history is complex and multifaceted, and it's important to consult multiple sources to get a comprehensive understanding of the events and the context.

Muslim armies of the past were able to maintain a high level of effectiveness in the field due to a number of factors. One important factor was the strong sense of religious and cultural unity among the soldiers, which helped to increase morale and cohesion within the ranks. Additionally, Muslim armies were often well-trained and disciplined, and had access to advanced military technology and tactics.

Additionally, the Muslim empire was vast and diverse and the armies were composed of soldiers from various ethnic groups and regions, this diversity could be a source of strength as well as a problem, as it could lead to difficulties in communication and coordination.

Another important aspect that helped Muslim armies to maintain their effectiveness was the ability to draw on the resources of the vast Islamic empire and the support of the population. This gave them a logistical advantage over their opponents, as well as a steady stream of new recruits.

It's important to note that this is a generalization and it could vary depending on the period of time, the specific army, and the context.