diff -ur -Xfreeciv/diff_ignore freeciv/ai/aiunit.c freeciv-mod/ai/aiunit.c
--- freeciv/ai/aiunit.c	Sun Jun  4 04:30:51 2000
+++ freeciv-mod/ai/aiunit.c	Sun Jun  4 04:29:59 2000
@@ -380,15 +380,25 @@
   int i, j;
   struct city *pcity;
   int x, y;
+
   if (dest) { x = punit->goto_dest_x; y = punit->goto_dest_y; }
   else { x = punit->x; y = punit->y; }
+
   for (j = y - n; j <= y + n; j++) {
     if (j < 0 || j >= map.ysize) continue;
     for (i = x - n; i <= x + n; i++) {
       pcity = map_get_city(i, j);
-      if (pcity && pcity->owner != punit->owner)
-        if (dest || punit->activity != ACTIVITY_GOTO || !has_defense(pcity))
+      if (pcity && pcity->owner != punit->owner) {
+        if (pcity->ai.wait[punit->owner]) {
+          freelog(LOG_DEBUG,"%s ignore too well protected city %s.",
+	           game.players[punit->owner].name,pcity->name);
+          pcity->ai.invasion = 0;
+          return;
+          }
+        if (dest || punit->activity != ACTIVITY_GOTO || !has_defense(pcity)) { 
           pcity->ai.invasion |= which;
+	  }
+      }
     }
   }
 }
@@ -1133,6 +1143,11 @@
     if (aplayer != pplayer) { /* enemy */
       city_list_iterate(aplayer->cities, acity)
         if (handicap && !map_get_known(acity->x, acity->y, pplayer)) continue;
+	if (acity->ai.wait[pplayer->player_no]) {
+	   freelog(LOG_DEBUG,"player %s ignore too well protected town %s.",
+		   pplayer->name,acity->name);
+	   continue;
+	   }
         sanity = (goto_is_sane(pplayer, punit, acity->x, acity->y, 1) &&
                  warmap.cost[acity->x][acity->y] < maxd); /* for Tangier->Malaga */
         if (ai_fuzzy(pplayer,1) && ((is_ground_unit(punit) &&
diff -ur -Xfreeciv/diff_ignore freeciv/common/city.h freeciv-mod/common/city.h
--- freeciv/common/city.h	Sun Jun  4 04:30:57 2000
+++ freeciv-mod/common/city.h	Sun Jun  4 04:30:13 2000
@@ -278,6 +278,13 @@
 /* so we can contemplate with warmap fresh and decide later */
   int settler_want, founder_want; /* for builder (F_SETTLERS) and founder (F_CITIES) */
   int a, f, invasion; /* who's coming to kill us, for attack co-ordination */
+  int lost[MAX_NUM_PLAYERS + MAX_NUM_BARBARIANS];
+  /* number of units lost to defend the town vs this player */
+  int killed[MAX_NUM_PLAYERS + MAX_NUM_BARBARIANS];
+  /* number of units killed while attacking this city by this player */
+  int wait[MAX_NUM_PLAYERS + MAX_NUM_PLAYERS];
+  /* this player will have to wait 'wait' turns before retrying to
+     attack this city. */
 };
 
 struct city {
diff -ur -Xfreeciv/diff_ignore freeciv/server/cityhand.c freeciv-mod/server/cityhand.c
--- freeciv/server/cityhand.c	Sun Jun  4 04:31:12 2000
+++ freeciv-mod/server/cityhand.c	Sun Jun  4 04:30:22 2000
@@ -191,6 +191,13 @@
   memset(pcity->ai.building_want, 0, sizeof(pcity->ai.building_want));
   pcity->ai.workremain = 1; /* there's always work to be done! */
   pcity->ai.danger = -1; /* flag, may come in handy later */
+  memset(pcity->ai.lost,0,
+	 (MAX_NUM_PLAYERS + MAX_NUM_BARBARIANS) * sizeof(int));
+  memset(pcity->ai.killed,0,
+	 (MAX_NUM_PLAYERS + MAX_NUM_BARBARIANS) * sizeof(int));
+  memset(pcity->ai.wait,0,
+	 (MAX_NUM_PLAYERS + MAX_NUM_BARBARIANS) * sizeof(int));
+
   pcity->corruption = 0;
   pcity->shield_bonus = 100;
   pcity->tax_bonus = 100;
diff -ur -Xfreeciv/diff_ignore freeciv/server/cityturn.c freeciv-mod/server/cityturn.c
--- freeciv/server/cityturn.c	Sun Jun  4 04:31:17 2000
+++ freeciv-mod/server/cityturn.c	Sun Jun  4 04:30:22 2000
@@ -88,6 +88,7 @@
 
 static void worker_loop(struct city *pcity, int *foodneed,
 			int *prodneed, int *workers);
+static void city_update_military_past (struct city * pcity);
 
 /**************************************************************************
 calculate the incomes according to the taxrates and # of specialists.
@@ -1509,6 +1510,7 @@
 
   city_check_workers(pplayer, pcity);
   city_refresh(pcity);
+  city_update_military_past (pcity);
 
   if (!city_got_effect(pcity,B_GRANARY) && !pcity->is_building_unit &&
     (pcity->currently_building == B_GRANARY) && (pcity->food_surplus > 0)
@@ -1649,4 +1651,35 @@
 	  get_nation_name_plural(pplayer->nation));
 
   remove_city(pcity);
+}
+
+/**************************************************************************
+  These lines prevent AI to loose too many units on too well protected city
+**************************************************************************/
+
+static void city_update_military_past (struct city * pcity)
+{
+  int i;
+
+  for(i=0;i< game.nplayers;i++)
+    if (pcity->ai.wait[i] < 0) {
+       pcity->ai.wait[i] = 0;
+       pcity->ai.killed[i] = 0;
+       pcity->ai.lost[i] = 0;
+       /* to prevent any problem of initialization */
+       }
+    else if (pcity->ai.wait[i]) {
+       pcity->ai.wait[i]--;
+       if (!pcity->ai.wait[i])
+          freelog(LOG_NORMAL,"%s can now retry to conquer city %s.",
+	          game.players[i].name,pcity->name);
+       } 
+    else if (pcity->ai.killed[i] / 2> pcity->ai.lost[i] + 1) {
+       pcity->ai.wait[i] = 25; /* 25 turns without figth */
+       pcity->ai.killed[i] = 0;
+       pcity->ai.lost[i] = 0;
+       freelog(LOG_NORMAL,"%s has lost too many units against city %s.",
+	       game.players[i].name,pcity->name);
+       }
+    /* else fight will go on */
 }
diff -ur -Xfreeciv/diff_ignore freeciv/server/unithand.c freeciv-mod/server/unithand.c
--- freeciv/server/unithand.c	Sun Jun  4 04:31:21 2000
+++ freeciv-mod/server/unithand.c	Sun Jun  4 04:30:22 2000
@@ -539,6 +539,22 @@
   
   unit_versus_unit(punit, pdefender);
 
+  if ((pcity=map_get_city(def_x,def_y)) ||
+      ((punit->activity == ACTIVITY_GOTO) && 
+       (pcity=map_get_city(punit->goto_dest_x,punit->goto_dest_y)))) {
+     /* if a unit is going to attack a city and is intercepted before
+	reaching the city, the result of the action will affect
+	the destination city. 
+	The case of a boat sunk while transporting units to attack a city
+	is not implemented. -- nb */
+	
+     if (punit->hp) {
+        pcity->ai.lost[punit->owner]++;	
+	} else {
+        pcity->ai.killed[punit->owner]++;	
+	}
+     }
+
   /* Adjust attackers moves_left _after_ unit_versus_unit() so that
    * the movement attack modifier is correct! --dwp
    *