In various figurative uses. Obsolete.

in figurative reference to the protection symbolized by a national flag floating over a place.

Protection or security afforded by a specified person, group, institution, etc. Chiefly in in a person's safeguard, in (or under) (the) safeguard of…

a person or group of people placed in a line of fire, or near a potential target, to deter or protect from an attack, esp. a group of civilians…

Authority, protection, means of defence; controlling or unifying agency. Frequently in under the umbrella and variants.