Both Uses

indicate
in
Lee Surrenders to Grant
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General Grant then continued: "Yes, I think our correspondence indicated pretty clearly the action that would be taken at our meeting; and I hope it may lead to a general suspension of hostilities and be the means of preventing any further loss of life."†

indicated = showed
Lee inclined his head as indicating his accord with this wish, and General Grant then went on to talk at some length in a very pleasant vein about the prospects of peace.†
*

indicating = showing

Definitions:

(1) (indicate)
to show (point out, demonstrate, express, or suggest)

The form, indicator can refer to many different kinds of things including intentional signals (such as a turn indicator), gauges (such as one that indicates pressure), or a measurement (such as an economic or chemical indicator).
(2) (meaning too rare to warrant focus)