Invasion. It was a terrible word, and one unthinkable in the context of a city like Canterlot. The very heart of Equestrian civilization, this bastion of pony culture had always seemed untouchable to those who saw it. Well, it was untouchable no longer, as a swarm of mysterious creatures, the Changelings, had descended upon the city. The protective barrier guarding against attackers had shattered, and dozens, if not hundreds of these bizarre invaders had begun pouring into the now-unprotected city. There was panic in the streets, and rightly so, as entire families were scrambling to get away from the insectoid aggressors. But among all those fleeing or breaking down under the stress, there was a lone mare charging at full pelt towards what was, admittedly, an unremarkable-looking building. This chestnut-brown earth pony, seeing the devastation around her, narrowed her eyes as she approached the front door of the building, bursting through it before slamming it right behind her. After taking just a few moments to catch her breath, she called out.
"Willow? Are you there?!"
Before long, another mare, a younger pegasus, poked her head out from one of the doors in the hallway.
"Hazel? Is that you?"
Hazel's face broke out into a smile, and she rushed forward, embracing her friend.
"I thought those things had got you!"
Willow shook her head as she returned the hug.
"N...no. I was in here doing some tidying up when the attack started."
Hazel, pulling away from her, sighed.
"Has anypony else turned up?"
Willow turned, pointing to another door.
"Just Granite and Skipper."
Hazel gave a firm nod, heading straight for the designated door, with Willow close behind. They entered, and immediately they saw that there was a dire situation. Their colleagues, Granite and Skipper, a unicorn and pegasus respectively, were indeed there, but they had their hooves full at the moment. There was now another pony with them, a mare, who was breathing heavily while Granite knelt beside her, holding her hoof.
"It's okay. You're gonna be fine," he said calmly.
As she entered the room in earnest, Hazel saw that this unknown mare's left hind leg was bandaged, from which she could see that there was blood behind it.
"What happened?"
Granite looked to her with concern.
"When those creatures struck some of the buildings, debris fell to the street below. Posey here got the brunt of some of it."
Posey looked to him.
"I'm sorry. There's so many in trouble, and..."
But Granite put his hoof on her shoulder, offering a kindly smile.
"You have nothing to apologise for. I'm just sorry I don't have my proper equipment with me. Please, just rest here, okay?"
Posey nodded, accepting her "Doctor's orders" and simply laying there, her breathing still heavy. Getting to his hooves, Granite looked to Hazel more seriously.
"How bad is it out there now?"
Hazel frowned.
"Probably worse than it was when you got in here."
Skipper, who'd been staring out of the window to make sure none of the invaders were coming for them, looked back to her.
"What are these things, Hazel?!"
Hazel shook her head.
"No clue. And right now, I don't care. We still have a job to do, and by Celestia we're gonna do it!"
Willow seemed aghast by that.
"But we don't have our full team here! Most of them left the city already!"
Hazel grunted with irritation.
"Ugh! Who's idea was it to give so many a vacation today?"
Granite sighed.
"Princess Cadance, I think. Apparently she suggested it to Princess Celestia as part of the celebration for her wedding. You know, give everypony a day off?"
Hazel rolled her eyes.
"Of all the times for us to be under-staffed!"
She rubbed her temples briefly.
"Okay, we'll just have to make do with what we have!"
Skipper chortled, but it was a dry laugh at best.
"And just what good can we do against a whole army?!"
Hazel frowned at him.
"We're not fighting, Skipper, we're doing our jobs! There's a lot of scared and hurt ponies out there who'll need help. We may not have all our team here, or even all our stuff, but we can still help."
She looked to Willow.
"These creatures, where are they?"
Willow, slightly taken aback at suddenly being asked such a question, stumbled for a moment.
"Oh! Um...they..."
She thought about it for a moment, then walked right past Hazel. Everypony in the room watched as she trotted right up to a large map of the city that was posted in a nearby wall, then unceremoniously tore it off. They all gave her some space, seeing her lay the map on the table in the middle of the room, before grabbing hold of a small pen on the side. She began circling different parts of the map, explaining herself as she did so.
"From what we've heard, the creatures are largely around the palace and the barracks."
Skipper groaned.
"So, going for our leaders and fighters. Isn't that just lovely?" he said sarcastically.
Hazel too stared at the map.
"We need to get ponies out of here. As many as we can as fast as we can."
She looked up to Granite.
"The main city gates?"
Granite shook his head.
"No dice. I ran by the place on the way here, while carrying Posey. The place is crawling with them."
Though disappointed, Hazel nevertheless nodded.
"Alright...what about the train station?"
Skipper was next to speak.
"All the trains were taken off the lines before the wedding. A royal decree that they be given a look-over. You know, annual maintenance sort of stuff?"
Hazel narrowed her eyes.
"Let me guess...another command from Princess Cadance?"
The uncomfortable silence was her only answer, and she slapped her forehead in frustration.
"Ugh! What was that mare thinking with all this?! Doesn't she know how important all this stuff is?!"
Granite shrugged.
"She couldn't have known an attack was going to happen, Hazel."
Hearing her colleague's words, Hazel calmed herself, if only by a little.
"...You're right...complaining about stuff in hindsight isn't gonna help anypony."
Again, she looked to the map.
"Are there any other places we can get ponies out?"
Skipper walked over, looking to the map intently.
"Er...oh! These places here!"
He pointed to a few spots on the outer walls of the city.
"These old gates have been ignored for years. I remember going through them with my sisters when we were kids."
He chuckled.
"Our Mother always gave us an earful of course, but hey, they're still open."
Hazel nodded.
"Let's hope those bugs don't know about them then."
She glanced around the room, seeing the look of fear and despondency on everypony's faces. In truth, she felt it herself, and more than just a little bit, but right now they had no choice.
"I know things look bleak, but we have to keep going with this. Our job is important, and we have to prioritize the safety of the citizens."
Skipper looked to her with disbelief and incredulity.
"What chance do we have here?! We were never trained for anything like this! We're supposed to deal with fires and disease outbreaks! Not...not invasions!"
Hazel nodded.
"A disaster is still a disaster, and we all have the training to deal with it. This might not be the exact scenario our leaders had in mind for us, but we can still help."
Granite looked to her, his face worn out from how tired he was.
"We don't even have leaders right now. They're either out of the city on their vacation or holed up somewhere where the bugs are!"
He glanced to Skipper.
"All we have is him, and he's an aide to an aide to an aide!"
Though he'd usually chafe at such a remark, Skipper sighed.
"He's right. We've got nopony to help us get through this."
Hazel called them all to attention by slamming her hoof down on the table.
"Have we ever needed direct orders to go out and help ponies before?!"
The stunned silence that followed was her answer, and after taking a moment to calm herself, she continued.
"Look...I know this is overwhelming, but there are stallions, mares and foals out there who are in even worse situations than us right now. They're lost, scared, hiding..."
She quickly looked to Posey.
"...even hurt. And we have our responsibilities. We find them, we do what we can for them, and we get them out of the city. If we're careful, and if we keep them calm, we might be able to get out of this mess before those creatures notice us."
The others all looked to each other. She was right, and they knew it. Come Tartarus or high water, they would do their duties, however un-praised or unglamorous it may be. They nodded to one another, then back to Hazel, who smiled to them all.
"Alright then. Granite, get whatever medical equipment you can get your hooves on in here. Willow, you help him go out and find any who are injured. But stick to the back-alleys when travelling. We don't want to risk being seen in the open."
The two said nothing in response, and simply charged out of the room, ready to do their vital work. Now alone with him, Hazel looked to Skipper.
"And as for you, you're with me. I'll need you to help me get volunteers to join us in this."
Skipper frowned, looking out of the window to the scene of continuing panic playing out in the streets.
"You think anypony will actually want to help at a time like this?"
Though unexpected, a look of hope came to Hazel's face.
"We're trying to help, aren't we?"
Skipper had no sarcastic remark for that, and so simply gave a grim nod. Turning, Hazel walked over to a nearby cabinet, opening it up and pulling out a single item, a hardhat, which she dutifully placed over her head.
"Alright then...time to do our jobs."
Author's Note
Whenever big battles occur in stories like this, who tends to get the most attention? The leaders who keep a cool head in a crisis? The armies who fight off the enemy? All worthy of our focus and praise. But there's another group that, in real life, would also be present, and provide just as valuable a service as those who lead or fight. And that's the people on the ground providing aid and assistance to those in need.
Emergency response teams, fire-prevention groups, field medics, those responsible for evacuations, all the people whose job it is to ensure the wellbeing of civilians during times of crisis, even in times of war. People like that do enormously valuable work, and I decided it would be interesting to make a story where they were the focus 
