Most Civil War reenacting events require that reenactors register for the event.  The reasons for registering are obvious:  It allows event organizers to know who is at the event and it helps them in contacting a reenactor to pass on a message should a family or personal emergency arise.

Information usually needed when registering are such things as name, address, age (if under 18 years old), reenactor unit name and emergency contact names and phone numbers.  

Most events allow and prefer pre-registration a month or two in advance of the event.  This helps organizers know the number of reenactors to expect at their event and helps them to prepare for the event in a logistical sense.  Some event organizers will allow "walk-on" registration, but some will not.  So in those cases when "walk-ons" are not allowed, if you haven't pre-registered you can't play soldier!

Most events require a monetary fee be paid by the reenactors who attend.  This fee can range from as low as $5.00 to as high as $25.00 to $30.00.  At most events, if you pre-register the fee is as much as $5.00 less than if you just "walk-on" and register. 

Registration fees are usually collected to help run the event, pay for the expenses of having the event, help to preserve National Historic Sites and Battlefields, etc.  Since most events are run by non-profit organizations, money collected from reenactors and spectators is used to help fund the event, not to make a profit for the organization.

NOTE: 

For SPHRS members, our Captain usually takes care of registering for any event our unit attends.  Prior to an event (usually a month or two before), the Captain will send out an email inquiring as to who is interested in attending the particular event. 

Once he knows who is interested, he will request the members mail to him their fees for the event.  Checks should always be made out to "SPHRS", not to the Captain. 

Once the Captain has collected all fees, he will pre-register everyone attending the event.  So, when we arrive at the event, everything is paid up and we are registered, etc.    

 On rare occassions, each member may have to register themselves over the internet for an event (if required by organizers), but this is the exception not the rule.