The/Our orders were to evacuate the area.

Why are you considering a subjunctive, when an order is an order? A 'suggestion' might be phrased in that way: "the suggestion was that we should evacuate the area"; or "the suggestion was that we evacuate the area." The sentence as given sounds unnatural.

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Note added at 10 hrs (2007-01-11 16:41:35 GMT)
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My feeling is that if an order isn't an order, an unequivocal command, then the organisation issuing it isn't an army. I've heard the Israeli army is pretty democratic and the Canadian army spokespersons I hear talking about Afghanistan on the radio, at the level of generals and major generals, project a tearful sensitivity that suggests debate and discussion of orders is welcome and that any refusal to follow orders in the field would be met with counselling. Perhaps it depends on the historical period. If the text dates from a period where a refusal to follow orders furnished grounds for court-martial, the subjunctive is probably out of place. 'Should' is also possible if it's contained in the order -- for example, it might not be possible to evacuate the area, if resistance is too great, and so the order might simply say something like 'The unit shall attempt to break-out...' In this case the author, indirectly quoting the essence of the orders, might say that the orders were 'that we should evacuate the area'. And 'shall' in direct speech can be reported indirectly as 'should' as well...