"oh, the fight is going to start!" cried nan, in high excitement. "see them coming up the hill!"

"will they shoot?" asked flossie, just a bit nervously.

"course they won't shoot," answered freddie. "can't shoot snowballs. ain't got no powder in."

the attacking party was still a good distance from the fort when those inside let fly a volley of snowballs. but the snowballs did not reach their mark, and still the others came up the hill.

"now then, give it to them!" cried bert, and let fly his first snowball, which landed on the top of the fort's wall. soon the air was full of snowballs, flying one way and another. many failed to do any damage, but some went true, and soon bert received a snowball full in the breast and another in the shoulder. then he slipped and fell and his own snowballs were lost.

the attacking party got to within fifty feet of the fort, but then the ammunition gave out and they were forced to retreat, which they did in quick order.

"hurrah! they can't take the fort!" cried those inside of the stronghold, and blew their horns more wildly than ever. but their own ammunition was low and they made other snowballs as quickly as they could, using the pile of snow in the middle of the fort for that purpose.

back of the barn the attacking party held a consultation.

"i've got a plan," said a boy named ned brown. "let us divide into two parties and one move on the fort from the front and the other from the back. then, if they attack one party, the other party can sneak in and climb over the fort wall and capture the flag."

"all right, let us do that," said bert.

waiting until each boy had a dozen or more snowballs, half of the attacking force moved away along a fence until the rear of the fort was gained. then, with another cheer, all set out for the fort.

it was a grand rush and soon the air was once more filled with snowballs, much to the delight of the spectators, who began to cheer both sides.

"oh, i hope they get into the fort this time," said nan.

"i hope they don't," answered another girl, who had a brother in the fort.

inside the fort the boys were having rather a hard time of it. they were close together, and a snowball coming over the walls was almost certain to hit one or another. more than this, the pile of snow around the flag was growing small, so that the flag was in great danger of toppling over.

up the two sides of the hill came the invaders, bert leading the detachment that was to attack the rear. he was hit again, but did not falter, and a moment later found himself at the very wall.

"get back there!" roared a boy from the fort and threw a large lump of soft snow directly into his face. but bert threw the lump back and the boy slipped and fell flat. then, amid a perfect shower of snowballs, bert and two other boys fairly tumbled into the fort.

"defend the flag! defend the flag!" was the rallying cry of the fort defenders, and they gathered around the flag. the struggle was now a hand-to-hand one, in which nothing but soft snow was used, and nearly every boy had his face washed.

"get back there!" roared danny rugg, who was close to the flag, but as he spoke two boys shoved him down on his face in the snow, and the next moment bert and another boy of the invading party had the flag and was carrying it away in triumph.

"the fort has fallen!" screamed nan, and clapped her hands.

"hurrah!" shouted freddie. "the—the forters are beaten, aren't they?"

"yes, freddie."

a cheer was given for those who had captured the fort. then some of the boys began to dance on the top of the walls, and down they came, one after another, until the fort was in ruins, and the great contest came to an end.

"it was just splendid!" said nan to bert, on the way home. "just like a real battle."

"only the band didn't play," put in freddie disappointedly. "real soldiers have a band. they don't play fish-horns."

"oh, freddie!" cried flossie. "they weren't fish-horns. they were christmas horns."

"it's all the same. i like a band, with a big, fat bass-drum."

"we'll have the band next time—just for your benefit, freddie," said bert.

he was tired out and glad to rest when they got home. more than this, some of the snow had gotten down his back, so he had to dry himself by sitting with his back to the sitting-room heater.

"danny rugg was terribly angry that we captured the fort," said he. "he is looking for the boys who threw him on his face."

"it served him right," answered nan, remembering the trouble over the broken show window.

the second fall of snow was followed by steady cold weather and it was not long before the greater part of lake metoka was frozen over. as soon as this happened nearly all of the boys and girls took to skating, so that sledding and snowballing were, for the time being, forgotten.

both nan and bert had new skates, given to them the christmas before, and each was impatient to go on the ice, but mrs. bobbsey held them back until she thought it would be safe.

"you must not go too far from shore," said she. "i understand the ice in the middle of the lake, and at the lower end, is not as firm as it might be."

freddie and flossie wanted to watch the skating, and nan took them to their father's lumber yard. here was a small office directly on the lake front, where they could see much that was going on and still be under the care of an old workman around the yards.

nan could not skate very well, but bert could get along nicely, and he took hold of his twin sister's hand, and away they went gliding over the smooth ice much to their combined delight.

"some day i am going to learn how to do fancy skating," said bert. "the dutch roll, and spread the eagle, and all that."

"there is mr. gifford," said nan. "let us watch him."

the gentleman mentioned was a fine skater and had once won a medal for making fancy figures on the ice. they watched him for a long while and so did many of the others present.

"it's beautiful to skate like that," cried nan, when they skated away. "it's just like knowing how to dance everything."

"only better," said bert, who did not care for dancing at all.

presently nan found some girls to skate with and then bert went off among the boys. the girls played tag and had great fun, shrieking at the top of their lungs as first one was "it" and then another. it was hard work for nan to catch the older girls, who could skate better, but easy enough to catch those of her own age and experience on the ice.

the boys played tag, too, and "snapped the whip," as it is termed. all of the boys would join hands in a long line and then skate off as fast as they could. then the boy on one end, called the snapper, would stop and pull the others around in a big curve. this would make the boys on the end of the line skate very fast, and sometimes they would go down, to roll over and over on the ice. once bert was at the end and down he went, to slide a long distance, when he bumped into a gentleman who was skating backwards and over went the man with a crash that could be heard a long distance off.

"hi! you young rascal!" roared the man, trying to scramble up. "what do you mean by bowling me over like that?"

"excuse me, but i didn't mean to do it," answered bert, and lost no time in getting out of the gentleman's way. the gentleman was very angry and left the ice, grumbling loudly to himself.

down near the lower end of mr. bobbsey's lumber yard some young men were building an ice-boat. bert and charley mason watched this work with interest. "let us make an ice-boat," said charley. "i can get an old bed-sheet for a sail, if you will get your father to give you the lumber."

"i'll try," answered bert, and it was agreed that the ice-boat should be built during the following week, after school.