List of oldest military units and formations in continuous operation

This is a list of oldest military units and formations in continuous operation.

Note: As the modern standing armies first developed in the 15th century, the terminology for modern military units and formations, such as company, battalion, regiment etc. mostly arose in the early modern period, during the 16th and 17th centuries.

Older military units no longer considered active
Entries in this table predate some of those listed above, but are no longer considered active.