Around the mid-1980's, what had been three separate area were recognized as being so intertwined that they became increasingly treated as a unified whole.
C3I is critical to making effective use of your resources. In a war, the enemy's C3I is the primary target (first hit, and continuing high-priority target). Since your C3I is your enemy's primary target, you need to prepare for significant disruption.
In a disaster, the "enemy" is the event that has significantly damaged the local infrastructure. We should expect that it has badly damaged the normal communications network, that many of the decision-makers are unavailable (either victims or out of position), and that many of the emergency responders in the field are so overloaded with tasks that they cannot report back an adequate picture of overall conditions.
People new to this area often underestimate the difficult of data fusion - combining the various pieces of data from various sources to produce a composite description. For example, consider the simple case where the decision-maker receives two reports containing related statistics from two people in roughly the same area.
Ambiguity of terminology is another likely problem. The word "casualty" is an example. For some, this is a synonym for "fatality", for others it means people injured but not killed, and for yet others, it covers both injured and killed. Since it is unrealistic to try to instruct people about "correct" usage, reporting templates should be designed with an eye to reducing opportunities for such confusions.
In emergencies and disasters, people often forget to communicate. For example, during the 2004-May-17 mountain lion sighting in Palo Alto, the police forgot to activate the emergency alerting system until long into the incident. The closer the communication system (who communicates with whom about what) is to that which is used in more common situations (normal business, minor emergencies,...), the more likely it is to be used in a disaster.